Exhibit 99.1

EXECUTION VERSION

NSTAR

Debt Securities

Underwriting Agreement

November 12, 2009

Banc of America Securities LLC

One Bryant Park

New York, NY 10036

Goldman, Sachs & Co.

85 Broad Street

New York, NY 10004

Ladies and Gentlemen:

From time to time NSTAR, a Massachusetts voluntary association under Chapter 182 of the General Laws of The Commonwealth of Massachusetts (the “Company”), proposes to enter into one or more Pricing Agreements (each a “Pricing Agreement”) in the form of Annex I hereto, with such additions and deletions as the parties thereto may determine, and, subject to the terms and conditions stated herein and therein, to issue and sell to the firms named in Schedule I to the applicable Pricing Agreement (such firms constituting the “Underwriters” with respect to such Pricing Agreement and the securities specified therein) certain of its debt securities (the “Securities”) specified in Schedule II to such Pricing Agreement (with respect to such Pricing Agreement, the “Designated Securities”).

The terms and rights of any particular issuance of Designated Securities shall be as specified in the Pricing Agreement relating thereto and in or pursuant to the indenture (the “Indenture”) identified in such Pricing Agreement.

1. Particular sales of Designated Securities may be made from time to time to the Underwriters of such Securities, for whom the firms designated as representatives of the Underwriters of such Securities in the Pricing Agreement relating thereto will act as representatives (the “Representatives”). The term “Representatives” also refers to a single firm acting as sole representative of the Underwriters and to an Underwriter or Underwriters who act without any firm being designated as its or their representatives. This Underwriting Agreement shall not be construed as an obligation of the Company to sell any of the Securities or as an obligation of any of the Underwriters to purchase the Securities. The obligation of the Company to issue and sell any of the Securities and the obligation of any of the Underwriters to purchase any of the Securities shall be evidenced by the Pricing Agreement with respect to the Designated Securities specified therein. Each Pricing Agreement shall specify the aggregate principal

amount of such Designated Securities, the initial public offering price of such Designated Securities, the purchase price to the Underwriters of such Designated Securities, the names of the Underwriters of such Designated Securities, the names of the Representatives of such Underwriters and the principal amount of such Designated Securities to be purchased by each Underwriter and shall set forth the date, time and manner of delivery of such Designated Securities and payment therefor. The Pricing Agreement shall also specify (to the extent not set forth in the Indenture and the registration statement and prospectus with respect thereto) the terms of such Designated Securities. A Pricing Agreement shall be in the form of an executed writing (which may be in counterparts), and may be evidenced by an exchange of telegraphic communications or any other rapid transmission device designed to produce a written record of communications transmitted. The obligations of the Underwriters under this Agreement and each Pricing Agreement shall be several and not joint.

2. The Company represents and warrants to, and agrees with, each of the Underwriters that:

(a) The Company has prepared and filed with the Securities and Exchange Commission (the “Commission”) an automatic shelf registration statement on Form S-3 (File No. 333-162401) to be used in connection with the public offering and sale of the Designated Securities (the “Initial Registration Statement”). The Initial Registration Statement became effective upon the filing with the Commission pursuant to Rule 462(e) of the rules and regulations of the Commission promulgated under the Securities Act of 1933, as amended (the “Act”), and no stop order suspending the effectiveness of the Initial Registration Statement or any post-effective amendment thereto has been issued and no proceeding for that purpose has been initiated or threatened by the Commission (the base prospectus filed as part of the Initial Registration Statement, in the form in which it has most recently been filed with the Commission on or prior to the date of this Agreement, is hereinafter called the “Basic Prospectus”; any preliminary prospectus (including any preliminary prospectus supplement) relating to the Designated Securities filed with the Commission pursuant to Rule 424(b) under the Act is hereinafter called a “Preliminary Prospectus”; the various parts of the Initial Registration Statement and any post-effective amendment thereto, including all exhibits and schedules thereto and all documents incorporated by reference in the Basic Prospectus but excluding any Form T-1 and including any prospectus supplement relating to the Designated Securities that is filed with the Commission and deemed by virtue of Rule 430B to be part of the Initial Registration Statement, each as amended at the time such part of the Initial Registration Statement became effective, are hereinafter collectively called the “Registration Statement”; the Basic Prospectus, as amended and supplemented immediately prior to the Applicable Time (as defined in Section 2(c) hereof), is hereinafter called the “Pricing Prospectus”; the form of the final prospectus relating to the Designated Securities filed with the Commission pursuant to Rule 424(b) under the Act in accordance with Section 5(a) hereof is hereinafter called the “Prospectus”; any reference herein to the Basic Prospectus, the Pricing Prospectus, any Preliminary Prospectus or the Prospectus shall be deemed to refer to and include the documents incorporated by reference therein pursuant to the applicable form under the Act, as of the date of such prospectus; any reference to any amendment or supplement to the Basic Prospectus, any Preliminary Prospectus or the Prospectus shall be deemed to refer to and include any post-effective amendment to the

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Registration Statement, any prospectus supplement relating to the Designated Securities filed with the Commission pursuant to Rule 424(b) under the Act and any documents filed under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and incorporated therein, in each case after the date of the Basic Prospectus, such Preliminary Prospectus or Prospectus, as the case may be; any reference to any amendment to the Initial Registration Statement shall be deemed to refer to and include any annual report of the Company filed pursuant to Section 13(a) or 15(d) of the Exchange Act after the effective date of the Initial Registration Statement that is incorporated by reference in the Registration Statement; and any “issuer free writing prospectus” as defined in Rule 433 under the Act relating to the Designated Securities is hereinafter called an “Issuer Free Writing Prospectus”;

(b) No order preventing or suspending the use of any Preliminary Prospectus or any Issuer Free Writing Prospectus has been issued by the Commission, and each Preliminary Prospectus, at the time of filing thereof, conformed in all material respects to the requirements of the Act and the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”) and the rules and regulations of the Commission thereunder, and did not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided , however , that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter of Designated Securities through the Representatives expressly for use therein;

(c) For the purposes of this Agreement, the “Applicable Time” means the time specified as such in the Pricing Agreement; the Pricing Prospectus as supplemented by the final term sheet prepared and filed pursuant to Section 5(a) hereof, taken together (collectively, the “Pricing Disclosure Package”) as of the Applicable Time, did not include any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; and each Issuer Free Writing Prospectus listed on Schedule III(a) to the Pricing Agreement does not conflict with the information contained in the Registration Statement, the Pricing Prospectus or the Prospectus, and each such Issuer Free Writing Prospectus, as supplemented by and taken together with the Pricing Disclosure Package as of the Applicable Time, did not include any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided , however , that this representation and warranty shall not apply to statements or omissions made in an Issuer Free Writing Prospectus in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter of Designated Securities through the Representatives expressly for use therein;

(d) The documents incorporated by reference in the Pricing Prospectus and the Prospectus, when they became effective or were filed with the Commission, as the case may be, conformed in all material respects to the requirements of the Act or the Exchange Act, as applicable, and the rules and regulations of the Commission thereunder,

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and none of such documents contained an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary to make the statements therein not misleading; and any further documents so filed and incorporated by reference in the Prospectus or any further amendment or supplement thereto, when such documents become effective or are filed with the Commission, as the case may be, will conform in all material respects to the requirements of the Act or the Exchange Act, as applicable, and the rules and regulations of the Commission thereunder and will not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; provided , however , that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter of Designated Securities through the Representatives expressly for use therein; and no such documents were filed with the Commission since the Commission’s close of business on the business day immediately prior to the date of this Agreement and prior to the execution of this Agreement, except as set forth on Schedule III(b) to the Pricing Agreement;

(e) The Registration Statement conforms, and the Prospectus and any further amendments or supplements to the Registration Statement or the Prospectus will conform, in all material respects to the requirements of the Act and the Trust Indenture Act and the rules and regulations of the Commission thereunder and do not and will not, as of the applicable effective date as to each part of the Registration Statement and as of the applicable filing date as to the Prospectus and any amendment or supplement thereto, contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; provided , however , that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter of Designated Securities through the Representatives expressly for use therein;

(f) At the time of filing the Initial Registration Statement, (ii) at the time of the most recent amendment thereto for the purposes of complying with Section 10(a)(3) of the Act (whether such amendment was by post-effective amendment, incorporated report filed pursuant to Section 13 or 15(d) of the Exchange Act or form of prospectus), (iii) at the earliest time after each of the times referred to in (i) and (ii) above that the Company or another offering participant made a bona fide offer within the meaning of Rule 164(h)(2) of the rules and regulations promulgated under the Act, (iv) at the time the Company or any person acting on its behalf (within the meaning, for this clause only, of Rule 163(c) of the Act) made any offer relating to the Designated Securities in reliance on the exemption of Rule 163 of the Act, (v) at the date and time the Registration Statement is deemed to be effective with respect to the underwriters pursuant to Rule 430B(f)(2), (vi) at the Applicable Time (with such time being used as the determination date for purposes of this clause (vi)) and (vii) at the Time of Delivery for the Designated Securities, the Company was and is a “well-known seasoned issuer” as defined in Rule 405 of the Securities Act and was not, is not and will not be an “ineligible issuer”, as defined in such Rule 405. The Registration Statement is an “automatic shelf registration statement,” as defined in Rule 405 of the Securities Act that has been filed with the

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Commission not earlier than three years prior to the date hereof, and the Company has not received from the Commission any notice pursuant to Rule 401(g)(2) of the Act objecting to use of the automatic shelf registration statement form.

(g) Neither the Company nor any of its subsidiaries has sustained since the date of the latest audited financial statements included or incorporated by reference in the Pricing Prospectus any material loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth or contemplated in the Pricing Prospectus; and, since the respective dates as of which information is given in the Registration Statement and the Pricing Prospectus, there has not been any change in the capital stock or long-term debt of the Company or any of its subsidiaries or any material adverse change, or any development involving a prospective material adverse change, in or affecting the general affairs, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, otherwise than as set forth or contemplated in the Pricing Prospectus;

(h) The Company has been duly organized and is lawfully existing as a voluntary association under Chapter 182 of the General Laws of The Commonwealth of Massachusetts, with power and authority to own its properties and conduct its business as described in the Pricing Prospectus;

(i) The Company has an authorized capitalization as set forth in the Pricing Prospectus, and all of the issued shares of beneficial interest of the Company have been duly and validly authorized and issued and are fully paid and non-assessable;

(j) The Securities have been duly authorized, and, when Designated Securities are issued and delivered pursuant to this Agreement and the Pricing Agreement with respect to such Designated Securities, such Designated Securities will have been duly executed, authenticated, issued and delivered and will constitute valid and legally binding obligations of the Company entitled to the benefits provided by the Indenture, which will be substantially in the form filed as an exhibit to the Registration Statement; the Indenture has been duly authorized and duly qualified under the Trust Indenture Act and, at the Time of Delivery for such Designated Securities (as defined in Section 4 hereof), the Indenture will constitute a valid and legally binding instrument, enforceable in accordance with its terms, subject, as to enforcement, to bankruptcy, insolvency, reorganization, moratorium and other laws of general applicability relating to or affecting creditors’ rights and to general equity principles; and the Indenture conforms, and the Designated Securities will conform, to the descriptions thereof contained in the Pricing Disclosure Package and the Prospectus;

(k) The issue and sale of the Securities and the compliance by the Company with all of the provisions of the Securities, the Indenture, this Agreement and any Pricing Agreement, and the consummation of the transactions herein and therein contemplated, will not conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company is a party or by which the

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Company is bound or to which any of the property or assets of the Company is subject, nor will such action result in any violation of the provisions of the Declaration of Trust or By-laws of the Company or any statute or any order, rule or regulation of any court or governmental agency or body having jurisdiction over the Company or any of its properties; and no consent, approval, authorization, order, registration or qualification of or with any such court or governmental agency or body is required for the issue and sale of the Securities or the consummation by the Company of the transactions contemplated by this Agreement or any Pricing Agreement or the Indenture, except such as have been, or will have been prior to the Time of Delivery, obtained under the Act and the Trust Indenture Act and such consents, approvals, authorizations, registrations or qualifications as may be required under state securities or Blue Sky laws in connection with the purchase and distribution of the Securities by the Underwriters;

(l) Neither the Company nor any of its subsidiaries is in violation of its Declaration of Trust, Articles of Organization or By-laws or in default in the performance or observance of any material obligation, agreement, covenant or condition contained in any indenture, mortgage, deed of trust, loan agreement, lease or other agreement or instrument to which it is a party or by which it or any of its properties may be bound;

(m) Other than as set forth in the Pricing Prospectus, there are no legal or governmental proceedings pending to which the Company or any of its subsidiaries is a party or of which any property of the Company or any of its subsidiaries is the subject which, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate have a material adverse effect on the current or future consolidated financial position, shareholders’ equity or results of operations of the Company and its subsidiaries; and, to the best of the Company’s knowledge, no such proceedings are threatened or contemplated by governmental authorities or threatened by others;

(n) The Company and its subsidiaries (i) are in compliance with any and all applicable foreign, federal, state and local laws and regulations relating to the protection of human health and safety, the environment or hazardous or toxic substances or wastes, pollutants or contaminants (“Environmental Laws”), (ii) have received and are in compliance with all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses, and (iii) have not received notice of any actual or potential liability under any Environmental Law or identified any actual or potential associated costs and liabilities (including, without limitation, any capital or operating expenditures required for clean-up, closure of properties or compliance with Environmental Laws, or permit, license or approval, any related constraints on operating activities and any potential liabilities to third parties), except where such non-compliance with Environmental Laws, failure to receive required permits, licenses or other approvals, or costs and/or liability would not, individually or in the aggregate, have a material adverse change in the condition (financial or otherwise), prospects, earnings, business or properties of the Company and its subsidiaries, taken as a whole, whether or not arising from transactions in the ordinary course of business, except as set forth in or contemplated in the Pricing Disclosure Package and the Prospectus (exclusive of any supplement thereto). Neither the Company nor any of its subsidiaries

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has been named as a “potentially responsible party” under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended, except where such designation would not, individually or in the aggregate, result in any actual or potential material adverse change in the condition (financial or otherwise), earnings, business or properties of the Company, and its subsidiaries, taken as a whole;

(o) The operations of the Company and its subsidiaries are and have been conducted at all times in compliance in all material respects with applicable financial recordkeeping and reporting requirements of the Currency and Foreign Transactions Reporting Act of 1970, as amended, and the rules and regulations promulgated thereunder (the “Money Laundering Act”), and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any of its subsidiaries with respect to the Money Laundering Act is pending;

(p) The Company and each of its subsidiaries maintain a system of internal accounting controls sufficient to provide reasonable assurance that (i) transactions are executed in accordance with management’s general or specific authorizations; (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain asset accountability; (iii) access to assets is permitted only in accordance with management’s general or specific authorization; and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences. The internal controls over financial reporting of the Company and its subsidiaries were effective as of December 31, 2008, and the Company and its subsidiaries were not aware of any material weakness in their internal control over financial reporting as of December 31, 2008;

(q) The Company and its subsidiaries maintain “disclosure controls and procedures” (as such term is defined in Rule 13a-15(e) under the Exchange Act); such disclosure controls and procedures were effective as of December 31, 2008;

(r) There is and has been no failure on the part of the Company and any of the Company’s directors or officers, in their capacities as such, to comply with any provision of the Sarbanes Oxley Act of 2002 and the rules and regulations promulgated in connection therewith (the “Sarbanes Oxley Act”) applicable to the Company, including Section 402 related to loans and Sections 302 and 906 related to certifications;

(s) The Company is not and, after giving effect to the offering and sale of the Securities and the application of the proceeds thereof as described in the Pricing Disclosure Package and the Prospectus, will not be an “investment company”, as such term is defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”);

(t) At the earliest time that the Company or an Underwriter made a bona fide offer (within the meaning of Rule 164(h)(2) under the Act) of the Designated Securities, the Company was not an “ineligible issuer” as defined in Rule 405 under the Act; and

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(u) PricewaterhouseCoopers LLP, who have audited certain financial statements of the Company and its subsidiaries, are independent public accountants as required by the Act and the rules and regulations of the Commission thereunder.

3. Upon the execution of the Pricing Agreement applicable to any Designated Securities and authorization by the Representatives of the release of such Designated Securities, the several Underwriters propose to offer such Designated Securities for sale upon the terms and conditions set forth in the Prospectus as amended or supplemented.

4. Designated Securities to be purchased by each Underwriter pursuant to the Pricing Agreement relating thereto, in the form specified in such Pricing Agreement, and in such authorized denominations and registered in such names as the Representatives may request upon at least forty-eight hours’ prior notice to the Company, shall be delivered by or on behalf of the Company to the Representatives for the account of such Underwriter, against payment by such Underwriter or on its behalf of the purchase price therefor by wire transfer of Federal (same-day) funds to the account specified by the Company to the Representatives at least forty-eight hours in advance or at such other place and time and date as the Representatives and the Company may agree upon in writing, such time and date being herein called the “Time of Delivery” for such Securities.

5. The Company agrees with each of the Underwriters of any Designated Securities:

(a) To prepare the Prospectus in relation to the applicable Designated Securities in a form approved by the Representatives and to file such Prospectus pursuant to Rule 424(b) under the Act not later than the Commission’s close of business on the second business day following the execution and delivery of the Pricing Agreement relating to the applicable Designated Securities or, if applicable, such earlier time as may be required by Rule 424(b); to make no further amendment or any supplement to the Registration Statement, the Basic Prospectus or Prospectus after the date of the Pricing Agreement relating to such Securities and prior to the Time of Delivery for such Securities which shall be disapproved by the Representatives for such Securities promptly after reasonable notice thereof; to advise the Representatives promptly of any such amendment or supplement after such Time of Delivery and furnish the Representatives with copies thereof; to prepare a final term sheet, containing solely a description of the Securities, in a form approved by you and attached to the Pricing Agreement as Annex IV thereto, and to file such term sheet pursuant to Rule 433(d) under the Act within the time required by such Rule; to file promptly all other material required to be filed by the Company with the Commission pursuant to Rule 433(d) under the Act; to file promptly all reports and any definitive proxy or information statements required to be filed by the Company with the Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act for so long as the delivery of a prospectus (or in lieu thereof, the notice referred to in Rule 173(a) under the Act) is required in connection with the offering or sale of such Securities, and during such same period to advise the Representatives, promptly after it receives notice thereof, of the time when any amendment to the Registration Statement has been filed or becomes effective or any supplement to the Prospectus or any amended Prospectus has been filed with the Commission, of the issuance by the Commission of any stop order or of any order

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preventing or suspending the use of any Preliminary Prospectus or other prospectus relating to the Securities, of the suspension of the qualification of such Securities for offering or sale in any jurisdiction, of the initiation or threatening of any proceeding for any such purpose, or of any request by the Commission for the amending or supplementing of the Registration Statement or Prospectus or for additional information; and, in the event of the issuance of any such stop order or of any such order preventing or suspending the use of any Preliminary Prospectus or other prospectus relating to the Securities or suspending any such qualification, to promptly use its best efforts to obtain the withdrawal of such order;

(b) If required by Rule 430B(h) under the Act, to prepare a form of prospectus in a form approved by you and to file such form of prospectus pursuant to Rule 424(b) under the Act not later than may be required by Rule 424(b) under the Act; and to make no further amendment or supplement to such form of prospectus which shall be disapproved by you promptly after reasonable notice thereof;

(c) Promptly from time to time to take such action as the Representatives may reasonably request to qualify such Securities for offering and sale under the securities laws of such jurisdictions as the Representatives may request and to comply with such laws so as to permit the continuance of sales and dealings therein in such jurisdictions for as long as may be necessary to complete the distribution of such Securities, provided that in connection therewith the Company shall not be required to qualify as a foreign corporation or to file a general consent to service of process in any jurisdiction;

(d) Prior to 10:00 a.m., New York City time, on the New York Business Day next succeeding the date of this Agreement and from time to time, to furnish the Underwriters with copies of the Prospectus in New York City in such quantities as the Representatives may reasonably request, and, if the delivery of a prospectus (or in lieu thereof, the notice referred to in Rule 173(a) under the Act) is required at any time in connection with the offering or sale of the Securities and if at such time any event shall have occurred as a result of which the Prospectus as then amended or supplemented would include an untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made when such prospectus (or in lieu thereof, the notice referred to in Rule 173(a) under the Act) is delivered, not misleading, or, if for any other reason it shall be necessary during such same period to amend or supplement the Prospectus or to file under the Exchange Act any document incorporated by reference in the Prospectus in order to comply with the Act, the Exchange Act or the Trust Indenture Act, to notify the Representatives and upon their request to file such document and to prepare and furnish without charge to each Underwriter and to any dealer in securities as many copies as the Representatives may from time to time reasonably request of an amended Prospectus or a supplement to the Prospectus which will correct such statement or omission or effect such compliance;

(e) To make generally available to its securityholders as soon as practicable, but in any event not later than eighteen months after the effective date of the Registration Statement (as defined in Rule 158(c) under the Act), an earnings statement of the

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Company and its subsidiaries (which need not be audited) complying with Section 11(a) of the Act and the rules and regulations of the Commission thereunder (including, at the option of the Company, Rule 158);

(f) During the period beginning from the date of the Pricing Agreement for such Designated Securities and continuing to and including the later of (i) the seventh day following the date of the Pricing Agreement for such Designated Securities and (ii) the Time of Delivery for such Designated Securities, not to offer, sell, contract to sell or otherwise dispose of any debt securities of the Company which mature more than one year after such Time of Delivery and which are substantially similar to such Designated Securities, without the prior written consent of the Representatives; and

(g) The Company agrees to pay the required Commission filing fees relating to the Designated Securities within the time required by Rule 456(b)(1) of the Act without regard to the proviso therein and otherwise in accordance with Rules 456(b) and 457(r) of the Act.

(ii) Each Underwriter represents and agrees that, without the prior consent of the Company and the Representatives, it has not made and will not make any offer relating to the Designated Securities that would constitute a free writing prospectus that is required to be filed with the Commission pursuant to Rule 433 under the Act; provided , however , that prior to the preparation of the final term sheet in accordance with Section 5(a) hereof, the Underwriters are authorized to use one or more term sheets containing customary information with respect to the final terms of the Securities in communications conveying information relating to the offering to prospective investors;

(iii) The Company represents that it has treated or agrees that it will treat each such term sheet the use of which has been consented to by the Company and the Representatives in accordance with Sections 6(a)(i) and 6(a)(ii) as an Issuer Free Writing Prospectus. Any such Issuer Free Writing Prospectus (including the final term sheet prepared and filed pursuant to Section 5(a) hereof) will be listed on Schedule III to the Pricing Agreement;

(b) The Company has complied and will comply with the requirements of Rule 433 under the Act applicable to any Issuer Free Writing Prospectus, including timely filing with the Commission or retention where required and legending; and

(c) The Company agrees that if at any time following issuance of an Issuer Free Writing Prospectus any event occurred or occurs as a result of which such Issuer Free Writing Prospectus would conflict with the information in the Registration

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Statement, the Pricing Prospectus or the Prospectus or would include an untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances then prevailing, not misleading, the Company will give prompt notice thereof to the Representatives and, if requested by the Representatives, will prepare and furnish without charge to each Underwriter an Issuer Free Writing Prospectus or other document which will correct such conflict, statement or omission; provided , however , that this representation and warranty shall not apply to any statements or omissions in an Issuer Free Writing Prospectus made in reliance upon and in conformity with information furnished in writing to the Company by an Underwriter through the Representatives expressly for use therein.

7. The Company covenants and agrees with the several Underwriters that the Company will pay or cause to be paid the following: (i) the fees, disbursements and expenses of the Company’s counsel and accountants in connection with the registration of the Securities under the Act and all other expenses in connection with the preparation, printing and filing of the Registration Statement, the Basic Prospectus, any Preliminary Prospectus, any Issuer Free Writing Prospectus and the Prospectus and amendments and supplements thereto and the mailing and delivering of copies thereof to the Underwriters and dealers; (ii) the cost of printing or producing any Agreement among Underwriters, this Agreement, any Pricing Agreement, any Indenture, any Blue Sky and Legal Investment Memoranda, closing documents (including any compilations thereof) and any other documents in connection with the offering, purchase, sale and delivery of the Securities; (iii) all expenses in connection with the qualification of the Securities for offering and sale under state securities laws as provided in Section 5(c) hereof, including the fees and disbursements of counsel for the Underwriters in connection with such qualification and in connection with the Blue Sky and Legal Investment Surveys; (iv) any fees charged by securities rating services for rating the Securities; (v) any filing fees incident to, and the fees and disbursements of counsel for the Underwriters in connection with, any required review by the Financial Industry Regulatory Authority of the terms of the sale of the Securities; (vi) the cost of preparing the Securities; (vii) the fees and expenses of any Trustee and any agent of any Trustee and the fees and disbursements of counsel for any Trustee in connection with any Indenture and the Securities; and (viii) all other costs and expenses incident to the performance of its obligations hereunder which are not otherwise specifically provided for in this Section. It is understood, however, that, except as provided in this Section, and Sections 9 and 12 hereof, the Underwriters will pay all of their own costs and expenses, including the fees of their counsel, transfer taxes on resale of any of the Securities by them, and any advertising expenses connected with any offers they may make.

8. The obligations of the Underwriters of any Designated Securities under the Pricing Agreement relating to such Designated Securities shall be subject, in the discretion of the Representatives, to the condition that all representations and warranties and other statements of the Company in or incorporated by reference in the Pricing Agreement relating to such Designated Securities are, at and as of the Time of Delivery for such Designated Securities, true and correct, the condition that the Company shall have performed all of its obligations hereunder theretofore to be performed, and the following additional conditions:

(a) The Prospectus shall have been filed with the Commission pursuant to Rule 424(b) within the applicable time period prescribed for such filing by the rules and

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regulations under the Act and in accordance with Section 5(a) hereof; the final term sheet contemplated by Section 5(a) hereof, and any other material required to be filed by the Company pursuant to Rule 433(d) under the Act, shall have been filed with the Commission within the applicable time periods prescribed for such filings by Rule 433; no stop order suspending the effectiveness of the Registration Statement or any part thereof shall have been issued and no proceeding for that purpose shall have been initiated or threatened by the Commission, and the Company has not received from the Commission any notice pursuant to Rule 401(g)(2) of the Act objecting to the use of the automatic shelf registration form; no stop order suspending or preventing the use of the Prospectus or any Issuer Free Writing Prospectus shall have been initiated or threatened by the Commission; and all requests for additional information on the part of the Commission shall have been complied with to the Representatives’ reasonable satisfaction;

(b) Counsel for the Underwriters shall have furnished to the Representatives such written opinion or opinions (a draft of each such opinion is attached as Annex III(a) hereto), dated the Time of Delivery for such Designated Securities, with respect to the organization of the Company, the validity of the Indenture, the Designated Securities, the Registration Statement, the Pricing Disclosure Package, the Prospectus and such other related matters as the Representatives may reasonably request, and such counsel shall have received such papers and information as they may reasonably request to enable them to pass upon such matters;

(c) One or more counsel for the Company satisfactory to the Representatives shall have furnished to the Representatives their written opinion (a draft of each such opinion is attached as Annex III(b) hereto), dated the Time of Delivery for such Designated Securities, in form and substance reasonably satisfactory to the Representatives, to the effect that:

(i) The Company has been duly formed and is lawfully existing as a voluntary association under Chapter 182 of the General Laws of The Commonwealth of Massachusetts, with power and authority to own its properties and conduct its business as described in the Prospectus as amended or supplemented;

(ii) This Agreement and the Pricing Agreement with respect to the Designated Securities have been duly authorized, executed and delivered by the Company;

(iii) The Designated Securities have been duly authorized, executed, authenticated, issued and delivered and constitute valid and legally binding obligations of the Company entitled to the benefits provided by the Indenture; and the Designated Securities and the Indenture conform as to matters of law to the descriptions thereof in the Prospectus;

(iv) The Indenture has been duly authorized, executed and delivered by the Company and constitutes a valid and legally binding instrument, enforceable

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in accordance with its terms, subject, as to enforcement, to bankruptcy, insolvency, reorganization, moratorium and other laws of general applicability relating to or affecting creditors’ rights and to general equity principles; and the Indenture has been duly qualified under the Trust Indenture Act;

(v) The issue and sale of the Designated Securities and the compliance by the Company with all of the provisions of the Designated Securities, the Indenture, this Agreement and the Pricing Agreement with respect to the Designated Securities, and the consummation of the transactions herein and therein contemplated will not conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument known to such counsel to which the Company is a party or by which the Company is bound or to which any of the property or assets of the Company is subject, nor will such actions result in any violation of the provisions of the Declaration of Trust or By-laws of the Company or any statute or any order, rule or regulation known to such counsel of any court or governmental agency or body having jurisdiction over the Company or any of its properties;

(vi) No consent, approval, authorization, order, registration or qualification of or with any such court or governmental agency or body is required for the issue and sale of the Designated Securities or the consummation by the Company of the transactions contemplated by this Agreement or such Pricing Agreement or the Indenture, except such as have been obtained under the Act and the Trust Indenture Act and such consents, approvals, authorizations, orders, registrations or qualifications as may be required under state securities or Blue Sky laws in connection with the purchase and distribution of the Designated Securities by the Underwriters;

(vii) The statements set forth in the Prospectus under the captions “Description of Debt Securities” and “Description of the Debentures”, insofar as they purport to constitute a summary of the terms of the Securities, and under the captions “Plan of Distribution” and “Underwriting”, insofar as they purport to describe matters of law and legal conclusions, are accurate and fair;

(viii) The Company is not and, after giving effect to the offering and sale of the Securities and the application of the proceeds thereof as described in the Pricing Disclosure Package and the Prospectus, will not be an “investment company”, as such term is defined in the Investment Company Act; and

(ix) The Registration Statement and the Prospectus and any further amendments and supplements thereto made by the Company prior to the Time of Delivery for the Designated Securities (other than the financial statements, including the notes and schedules thereto, or any financial or accounting data or assessment of or reports on the effectiveness of internal control over financial reporting, as to which such counsel need express no opinion) comply as to form in all material respects with the requirements of the Act and the Trust Indenture Act

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and the rules and regulations thereunder; although they do not assume any responsibility for the accuracy, completeness or fairness of the statements made or the information contained in the Registration Statement or the Prospectus, except to the extent referred to in the opinion in subsection (vii) of this Section 8(c), they have no reason to believe (A) that any part of the Registration Statement, or any further amendment thereto made by the Company prior to the Time of Delivery (other than the financial statements, including the notes and schedules thereto, or any financial or accounting data or assessments of or reports on the effectiveness of internal control over financial reporting, as to which such counsel need express no opinion), when such part or amendment became effective, contained an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary to make the statements therein not misleading or (B) that the Pricing Disclosure Package, as of the Applicable Time, contained any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading, or (C) that, as of its date and as of the Time of Delivery, the Prospectus or any further amendment or supplement thereto made by the Company prior to the Time of Delivery (other than the financial statements and related schedules therein, as to which such counsel need express no opinion) contained an untrue statement of a material fact or omitted to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; and they do not know of any amendment to the Registration Statement required to be filed or any contracts or other documents of a character required to be filed as an exhibit to the Registration Statement or required to be incorporated by reference into the Prospectus as amended or supplemented which are not filed or incorporated by reference as required;

(d) On the date of the Pricing Agreement for such Designated Securities at a time prior to the execution of the Pricing Agreement with respect to such Designated Securities and at the Time of Delivery for such Designated Securities, the independent accountants of the Company who have audited the financial statements of the Company and its subsidiaries included or incorporated by reference in the Registration Statement shall have furnished to the Representatives a letter, dated the effective date of the Registration Statement or the date of the most recent report filed with the Commission containing financial statements and incorporated by reference in the Registration Statement, if the date of such report is later than such effective date, and a letter dated such Time of Delivery, respectively, to the effect set forth in Annex II hereto, and with respect to such letter dated such Time of Delivery, as to such other matters as the Representatives may reasonably request and in form and substance satisfactory to the Representatives (a draft of the form of letter to be delivered on the date of the Pricing Agreement prior to the execution of the Pricing Agreement and on the effective date of any post-effective amendment to the Registration Statement, and as of each Time of Delivery is attached as Annex II hereto);

(e) (i) Neither the Company nor any of its subsidiaries shall have sustained since the date of the latest audited financial statements included or incorporated by

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reference in the Pricing Prospectus any loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth or contemplated in the Pricing Prospectus, and (ii) since the respective dates as of which information is given in the Pricing Prospectus there shall not have been any change in the capital stock or long-term debt of the Company or any of its subsidiaries or any change, or any development involving a prospective change, in or affecting the general affairs, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries, otherwise than as set forth or contemplated in the Pricing Prospectus, the effect of which, in any such case described in clause (i) or (ii), is in the judgment of the Representatives so material and adverse as to make it impracticable or inadvisable to proceed with the public offering or the delivery of the Designated Securities on the terms and in the manner contemplated in the Prospectus;

(f) On or after the Applicable Time, (i) no downgrading shall have occurred in the rating accorded the Company’s debt securities or preferred stock by any “nationally recognized statistical rating organization”, as that term is defined by the Commission for purposes of Rule 436(g)(2) under the Act, and (ii) no notice shall have been given of any intended or potential decrease in any such rating or of a possible change in any such rating that does not indicate the direction of the possible change;

(g) On or after the Applicable Time, there shall not have occurred any of the following: (i) a suspension or material limitation in trading in securities generally on the New York Stock Exchange; (ii) a general moratorium on commercial banking activities declared by either Federal or New York State authorities; or a material disruption in commercial banking or securities settlement or clearance services in the United States; (iii) the outbreak or escalation of hostilities or an act of terrorism involving the United States or the declaration by the United States of a national emergency or war; or (iv) the occurrence of any other calamity or crisis in the United States or elsewhere; if the effect of any such event specified in clause (iii) or (iv) in the judgment of the Representatives makes it impracticable or inadvisable to proceed with the public offering or the delivery of the Designated Securities on the terms and in the manner contemplated in the Prospectus;

(h) The Company shall have complied with the provisions of Section 5(c) hereof with respect to the furnishing of prospectuses on the New York Business Day next succeeding the date of this Agreement; and

(i) The Company shall have furnished or caused to be furnished to the Representatives at the Time of Delivery for the Designated Securities a certificate or certificates of officers of the Company satisfactory to the Representatives as to the accuracy of the representations and warranties of the Company herein at and as of such Time of Delivery, as to the performance by the Company of all of its obligations hereunder to be performed at or prior to such Time of Delivery, as to the matters set forth in subsections (a) and (e) of this Section and as to such other matters as the Representatives may reasonably request.

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9. (a) The Company will indemnify and hold harmless each Underwriter against any losses, claims, damages or liabilities, joint or several, to which such Underwriter may become subject, under the Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in any Preliminary Prospectus, the Registration Statement, the Basic Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, or any Issuer Free Writing Prospectus or any “issuer information” filed or required to be filed pursuant to Rule 433(d) under the Act, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and will reimburse each Underwriter for any legal or other expenses reasonably incurred by such Underwriter in connection with investigating or defending any such action or claim as such expenses are incurred; provided , however , that the Company shall not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission made in any Preliminary Prospectus, the Registration Statement, the Basic Prospectus, the Pricing Prospectus or the Prospectus, or any such amendment or supplement, or any Issuer Free Writing Prospectus, in reliance upon and in conformity with written information furnished to the Company by any Underwriter of Designated Securities through the Representatives expressly for use therein.

(b) Each Underwriter will indemnify and hold harmless the Company against any losses, claims, damages or liabilities to which the Company may become subject, under the Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in any Preliminary Prospectus, the Registration Statement, the Basic Prospectus, the Pricing Prospectus or the Prospectus, or any amendment or supplement thereto, or any Issuer Free Writing Prospectus, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in any Preliminary Prospectus, the Registration Statement, the Basic Prospectus, the Pricing Prospectus or the Prospectus, or any such amendment or supplement or any Issuer Free Writing Prospectus, in reliance upon and in conformity with written information furnished to the Company by such Underwriter through the Representatives expressly for use therein; and will reimburse the Company for any legal or other expenses reasonably incurred by the Company in connection with investigating or defending any such action or claim as such expenses are incurred.

(c) Promptly after receipt by an indemnified party under subsection (a) or (b) above of notice of the commencement of any action, such indemnified party shall, if a claim in respect thereof is to be made against the indemnifying party under such subsection, notify the indemnifying party in writing of the commencement thereof; but the omission so to notify the indemnifying party shall not relieve it from any liability which it may have to any indemnified party otherwise than under such subsection. In

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case any such action shall be brought against any indemnified party and it shall notify the indemnifying party of the commencement thereof, the indemnifying party shall be entitled to participate therein and, to the extent that it shall wish, jointly with any other indemnifying party similarly notified, to assume the defense thereof, with counsel satisfactory to such indemnified party (who shall not, except with the consent of the indemnified party, be counsel to the indemnifying party), and, after notice from the indemnifying party to such indemnified party of its election so to assume the defense thereof, the indemnifying party shall not be liable to such indemnified party under such subsection for any legal expenses of other counsel or any other expenses, in each case subsequently incurred by such indemnified party, in connection with the defense thereof other than reasonable costs of investigation. No indemnifying party shall, without the written consent of the indemnified party, effect the settlement or compromise of, or consent to the entry of any judgment with respect to, any pending or threatened action or claim in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified party is an actual or potential party to such action or claim) unless such settlement, compromise or judgment (i) includes an unconditional release of the indemnified party from all liability arising out of such action or claim and (ii) does not include a statement as to or an admission of fault, culpability or a failure to act, by or on behalf of any indemnified party. The indemnifying party shall not be required to indemnify an Indemnified Party for any amount paid or payable in the settlement or compromise of any action, proceeding or investigation effected without its written consent, which consent shall not be unreasonably withheld.

(d) If the indemnification provided for in this Section 9 is unavailable to or insufficient to hold harmless an indemnified party under subsection (a) or (b) above in respect of any losses, claims, damages or liabilities (or actions in respect thereof) referred to therein, then each indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of such losses, claims, damages or liabilities (or actions in respect thereof) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Underwriters of the Designated Securities on the other from the offering of the Designated Securities to which such loss, claim, damage or liability (or action in respect thereof) relates. If, however, the allocation provided by the immediately preceding sentence is not permitted by applicable law or if the indemnified party failed to give the notice required under subsection (c) above, then each indemnifying party shall contribute to such amount paid or payable by such indemnified party in such proportion as is appropriate to reflect not only such relative benefits but also the relative fault of the Company on the one hand and the Underwriters of the Designated Securities on the other in connection with the statements or omissions which resulted in such losses, claims, damages or liabilities (or actions in respect thereof), as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and such Underwriters on the other shall be deemed to be in the same proportion as the total net proceeds from such offering (before deducting expenses) received by the Company bear to the total underwriting discounts and commissions received by such Underwriters. The relative fault shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company on the one hand or such Underwriters on

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the other and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The Company and the Underwriters agree that it would not be just and equitable if contribution pursuant to this subsection (d) were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation which does not take account of the equitable considerations referred to above in this subsection (d). The amount paid or payable by an indemnified party as a result of the losses, claims, damages or liabilities (or actions in respect thereof) referred to above in this subsection (d) shall be deemed to include any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any such action or claim. Notwithstanding the provisions of this subsection (d), no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the applicable Designated Securities underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages which such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The obligations of the Underwriters of Designated Securities in this subsection (d) to contribute are several in proportion to their respective underwriting obligations with respect to such Securities and not joint.

(e) The obligations of the Company under this Section 9 shall be in addition to any liability which the Company may otherwise have and shall extend, upon the same terms and conditions, to each person, if any, who controls any Underwriter within the meaning of the Act; and the obligations of the Underwriters under this Section 9 shall be in addition to any liability which the respective Underwriters may otherwise have and shall extend, upon the same terms and conditions, to each officer and director of the Company and to each person, if any, who controls the Company within the meaning of the Act.

10. (a) If any Underwriter shall default in its obligation to purchase the Designated Securities which it has agreed to purchase under the Pricing Agreement relating to such Designated Securities, the Representatives may in their discretion arrange for themselves or another party or other parties reasonably satisfactory to the Company to purchase such Designated Securities on the terms contained herein. If within thirty-six hours after such default by any Underwriter the Representatives do not arrange for the purchase of such Designated Securities, then the Company shall be entitled to a further period of thirty-six hours within which to procure another party or other parties reasonably satisfactory to the Representatives to purchase such Designated Securities on such terms. In the event that, within the respective prescribed period, the Representatives notify the Company that they have so arranged for the purchase of such Designated Securities, or the Company notifies the Representatives that it has so arranged for the purchase of such Designated Securities, the Representatives or the Company shall have the right to postpone the Time of Delivery for such Designated Securities for a period of not more than seven days, in order to effect whatever changes may thereby be made necessary in the Registration Statement or the Prospectus as amended or supplemented,

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or in any other documents or arrangements, and the Company agrees to file promptly any amendments or supplements to the Registration Statement or the Prospectus which in the opinion of the Representatives may thereby be made necessary. The term “Underwriter” as used in this Agreement shall include any person substituted under this Section with like effect as if such person had originally been a party to the Pricing Agreement with respect to such Designated Securities.

(b) If, after giving effect to any arrangements for the purchase of the Designated Securities of a defaulting Underwriter or Underwriters by the Representatives and the Company as provided in subsection (a) above, the aggregate principal amount of such Designated Securities which remains unpurchased does not exceed one-eleventh of the aggregate principal amount of the Designated Securities, then the Company shall have the right to require each non-defaulting Underwriter to purchase the principal amount of Designated Securities which such Underwriter agreed to purchase under the Pricing Agreement relating to such Designated Securities and, in addition, to require each non-defaulting Underwriter to purchase its pro rata share (based on the principal amount of Designated Securities which such Underwriter agreed to purchase under such Pricing Agreement) of the Designated Securities of such defaulting Underwriter or Underwriters for which such arrangements have not been made; but nothing herein shall relieve a defaulting Underwriter from liability for its default.

(c) If, after giving effect to any arrangements for the purchase of the Designated Securities of a defaulting Underwriter or Underwriters by the Representatives and the Company as provided in subsection (a) above, the aggregate principal amount of Designated Securities which remains unpurchased exceeds one-eleventh of the aggregate principal amount of the Designated Securities, as referred to in subsection (b) above, or if the Company shall not exercise the right described in subsection (b) above to require non-defaulting Underwriters to purchase Designated Securities of a defaulting Underwriter or Underwriters, then the Pricing Agreement relating to such Designated Securities shall thereupon terminate, without liability on the part of any non-defaulting Underwriter or the Company, except for the expenses to be borne by the Company and the Underwriters as provided in Section 7 hereof and the indemnity and contribution agreements in Section 9 hereof; but nothing herein shall relieve a defaulting Underwriter from liability for its default.

11. The respective indemnities, agreements, representations, warranties and other statements of the Company and the several Underwriters, as set forth in this Agreement or made by or on behalf of them, respectively, pursuant to this Agreement, shall remain in full force and effect, regardless of any investigation (or any statement as to the results thereof) made by or on behalf of any Underwriter or any controlling person of any Underwriter, or the Company, or any officer or director or controlling person of the Company, and shall survive delivery of and payment for the Securities.

12. If any Pricing Agreement shall be terminated pursuant to Section 10 hereof, the Company shall not then be under any liability to any Underwriter with respect to the Designated Securities covered by such Pricing Agreement except as provided in Sections 7 and 9 hereof; but, if for any other reason Designated Securities are not delivered by or on behalf of the Company as

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provided herein, the Company will reimburse the Underwriters through the Representatives for all out-of-pocket expenses approved in writing by the Representatives, including fees and disbursements of counsel, reasonably incurred by the Underwriters in making preparations for the purchase, sale and delivery of such Designated Securities, but the Company shall then be under no further liability to any Underwriter with respect to such Designated Securities except as provided in Sections 7 and 9 hereof.

13. In all dealings hereunder, the Representatives of the Underwriters of Designated Securities shall act on behalf of each of such Underwriters, and the parties hereto shall be entitled to act and rely upon any statement, request, notice or agreement on behalf of any Underwriter made or given by such Representatives jointly or by such of the Representatives, if any, as may be designated for such purpose in the Pricing Agreement.

All statements, requests, notices and agreements hereunder shall be in writing, and if to the Underwriters shall be delivered or sent by mail, telex or facsimile transmission to the address of the Representatives as set forth in the Pricing Agreement; and if to the Company shall be delivered or sent by mail, telex or facsimile transmission to the address of the Company set forth in the Registration Statement: Attention: General Counsel, with a copy to Ropes & Gray LLP, Attention: David A. Fine; provided , however , that any notice to an Underwriter pursuant to Section 9(c) hereof shall be delivered or sent by mail, telex or facsimile transmission to such Underwriter at its address set forth in its Underwriters’ Questionnaire, or telex constituting such Questionnaire, which address will be supplied to the Company by the Representatives upon request. Any such statements, requests, notices or agreements shall take effect upon receipt thereof.

14. This Agreement and each Pricing Agreement shall be binding upon, and inure solely to the benefit of, the Underwriters, the Company and, to the extent provided in Sections 9 and 11 hereof, the officers and directors of the Company and each person who controls the Company or any Underwriter, and their respective heirs, executors, administrators, successors and assigns, and no other person shall acquire or have any right under or by virtue of this Agreement or any such Pricing Agreement. No purchaser of any of the Securities from any Underwriter shall be deemed a successor or assign by reason merely of such purchase.

15. Time shall be of the essence of each Pricing Agreement. As used herein, “business day” shall mean any day when the Commission’s office in Washington, D.C. is open for business.

16. The Company hereby acknowledges that (a) the purchase and sale of Designated Securities pursuant to each Pricing Agreement is an arm’s-length commercial transaction between the Company, on the one hand, and the Underwriters and any affiliate through which it may be acting, on the other, (b) the Underwriters are acting as principal and not as an agent or fiduciary of the Company and (c) the Company’s engagement of the Underwriters in connection with the offering and the process leading up to the offering is as independent contractors and not in any other capacity. Furthermore, the Company agrees that it is solely responsible for making its own judgments in connection with the offering (irrespective of whether any of the Underwriters has advised or is currently advising the Company on related other matters). The Company agrees that it will not claim that the Underwriters have rendered advisory services of any nature or respect, or owe an agency, fiduciary or similar duty to the Company, in connection with such transaction or the process leading thereto.

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17. Each Pricing Agreement supersedes all prior agreements and understandings (whether written or oral) between the Company and the Underwriters, or any of them, with respect to the subject matter thereof.

18. The Company hereby irrevocably waives, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to the Agreement or any Pricing Agreement or the transactions contemplated hereby and thereby.

19. This Agreement and each Pricing Agreement shall be governed by and construed in accordance with the laws of The Commonwealth of Massachusetts.

20. This Agreement and each Pricing Agreement may be executed by any one or more of the parties hereto and thereto in any number of counterparts, each of which shall be deemed to be an original, but all such respective counterparts shall together constitute one and the same instrument.

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If the foregoing is in accordance with your understanding, please sign and return to us seven counterparts hereof.

Accepted as of the date hereof:

Banc of America Securities LLC

Goldman, Sachs & Co.

EXECUTION COPY

Pricing Agreement

To the Representatives named

in Schedule II hereto.

November 12, 2009

Ladies and Gentlemen:

NSTAR, a Massachusetts voluntary association under Chapter 182 of the General Laws of The Commonwealth of Massachusetts (the “Company”), proposes, subject to the terms and conditions stated herein and in the Underwriting Agreement, dated November 12, 2009 (the “Underwriting Agreement”), between the Company, on the one hand, and Banc of America Securities LLC and Goldman, Sachs & Co., on the other hand, to issue and sell to the Underwriters named in Schedule I hereto (the “Underwriters”) the Securities specified in Schedule II hereto (the “Designated Securities”). Each of the provisions of the Underwriting Agreement is incorporated herein by reference in its entirety, and shall be deemed to be a part of this Agreement to the same extent as if such provisions had been set forth in full herein; and each of the representations and warranties set forth therein shall be deemed to have been made at and as of the date of this Pricing Agreement. Each reference to the Representatives herein and in the provisions of the Underwriting Agreement so incorporated by reference shall be deemed to refer to you. Unless otherwise defined herein, terms defined in the Underwriting Agreement are used herein as therein defined. The Representatives designated to act on behalf of the Representatives and on behalf of each of the Underwriters of the Designated Securities pursuant to Section 13 of the Underwriting Agreement and the address of the Representatives referred to in such Section 13 are set forth at the end of Schedule II hereto.

The Issuer Free Writing Prospectuses referred to in Section 6(a)(iii) of the Underwriting Agreement are set forth on Schedule III(a) hereto, and any additional documents incorporated by reference referred to in Section 2(d) of the Underwriting Agreement are set forth on Schedule III(b) hereto. The form of final term sheet referred to in Section 5(a) of the Underwriting Agreement is attached hereto as Schedule IV.

Subject to the terms and conditions set forth herein and in the Underwriting Agreement incorporated herein by reference, the Company agrees to issue and sell to each of the Underwriters, and each of the Underwriters agrees, severally and not jointly, to purchase from the Company, at the time and place and at the purchase price to the Underwriters set forth in Schedule II hereto, the principal amount of Designated Securities set forth opposite the name of such Underwriter in Schedule I hereto.

If the foregoing is in accordance with your understanding, please sign and return to us seven counterparts hereof, and upon acceptance hereof by you, on behalf of each of the Underwriters, this letter and such acceptance hereof, including the provisions of the Underwriting Agreement incorporated herein by reference, shall constitute a binding agreement

between each of the Underwriters and the Company. It is understood that your acceptance of this letter on behalf of each of the Underwriters is or will be pursuant to the authority set forth in a form of Agreement among Underwriters, the form of which shall be submitted to the Company for examination upon request, but without warranty on the part of the Representatives as to the authority of the signers thereof.

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Accepted as of the date hereof:

On behalf of each of the Underwriters

SCHEDULE II

Title of Designated Securities:

4.50% Debentures due 2019

Aggregate Principal Amount:

$350,000,000

Price to Public:

99.167% of the principal amount of the Designated Securities, plus accrued interest from November 17, 2009

Purchase Price by Underwriters:

98.517% of the principal amount of the Designated Securities, plus accrued interest from November 17, 2009

Form of Designated Securities:

Book-entry only form represented by one or more global securities deposited with The Depository Trust Company (“DTC”) or its designated custodian, to be made available for checking by the Representatives at least twenty-four hours prior to the Time of Delivery at the office of DTC.

Specified Funds for Payment of Purchase Price:

Federal (same-day) funds

Applicable Time:

1:00 p.m. (EST) on November 12, 2009

Time of Delivery:

9:30 a.m. (New York City time) on November 17, 2009

Indenture:

Indenture, dated as of January 12, 2000, between the Company and The Bank of New York Mellon Trust Company, N.A. (as successor Trustee to Bank One Trust Company, N.A.), as trustee, as supplemented or amended.

Maturity:

November 15, 2019

Interest Rate:

4.50% per annum

Interest Payment Dates:

May 15 and November 15, commencing on May 15, 2010

Redemption Provisions:

The Company may, at the option of the Company, redeem the Designated Securities, in whole or in part, at any time at a redemption price equal to the greater of:

The redemption price will be calculated assuming a 360-day year consisting of twelve 30-day months.

“Adjusted Treasury Rate” means, with respect to any redemption date, the rate per annum equal to the semiannual equivalent yield to maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for that redemption date.

“Comparable Treasury Issue” means the United States Treasury security selected by the Quotation Agent as having an actual or interpolated maturity comparable to the remaining term of the Designated Securities that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Designated Securities.

“Comparable Treasury Price” means, with respect to any redemption date:

“Quotation Agent” means the Reference Treasury Dealer appointed by us.

“Reference Treasury Dealer” means (i) each of Banc of America Securities LLC and Goldman, Sachs & Co. and their respective successors, unless any of them ceases to be a primary U.S. Government securities dealer in New York City (a “Primary Treasury Dealer”), in which case we shall substitute another Primary Treasury Dealer; and (ii) any other Primary Treasury Dealer selected by us.

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any redemption date, the average, as determined by the trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the trustee by that Reference Treasury Dealer at 5:00 p.m., New York City time, on the third business day preceding that redemption date.

The Company will mail notice of any redemption at least 30 days but not more than 60 days before the redemption date to each holder of the Designated Securities to be redeemed.

Unless the Company defaults in payment of the redemption price, on and after the redemption date, interest will cease to accrue on the Designated Securities or portions of the Designated Securities called for redemption.

Sinking Fund Provisions:

No sinking fund provisions

Defeasance Provisions: None

Closing Location for Delivery of Designated Securities: Choate, Hall & Stewart LLP, Two International Place, Boston, MA 02110 on November 17, 2009

Additional Closing Conditions: None

Names and address of Representatives:

SCHEDULE III

Final Pricing Term Sheet, dated November 12, 2009

None.

The issuer has filed a registration statement (including a prospectus) with the SEC for the offering to which this communication relates. Before you invest, you should read the prospectus in that registration statement and other documents the issuer has filed with the SEC for more complete information about the issuer and this offering.

You may get these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov. Alternatively, the issuer, any underwriter or any dealer participating in the offering will arrange to send you the prospectus if you request it by calling Banc of America Securities LLC toll free at 1-800-294-1322 or Goldman, Sachs & Co. toll free at 1-866-471-2526.

ANNEX II

Pursuant to Section 8(d) of the Underwriting Agreement, the accountants shall furnish letters to the Underwriters to the effect that:

(i) They are an independent registered public accounting firm with respect to the Company and its subsidiaries within the meaning of the Act and the applicable rules and regulations adopted by the Commission;

(ii) In their opinion, the financial statements and any supplementary financial information and schedules examined by them and included or incorporated by reference in the Registration Statement or the Prospectus comply as to form in all material respects with the applicable accounting requirements of the Act or the Exchange Act, as applicable, and the related rules and regulations; and, if applicable, they have made a review in accordance with standards established by the American Institute of Certified Public Accountants of the consolidated interim financial statements, selected financial data and/or condensed financial statements derived from audited financial statements of the Company for the periods specified in such letter, as indicated in their reports thereon, copies of which have been furnished to the representative or representatives of the Underwriters (the “Representatives”), such term to include an Underwriter or Underwriters who act without any firm being designated as its or their representatives;

(iii) They have made a review in accordance with standards established by the American Institute of Certified Public Accountants of the unaudited condensed consolidated statements of income, consolidated balance sheets and consolidated statements of cash flows included in the Prospectus and/or included in the Company’s quarterly reports on Form 10-Q incorporated by reference into the Prospectus as indicated in their reports thereon included in such quarterly reports; and on the basis of specified procedures including inquiries of officials of the Company who have responsibility for financial and accounting matters regarding whether the unaudited condensed consolidated financial statements referred to in paragraph (vi)(A)(i) below comply as to form in all material respects with the applicable accounting requirements of the Act and the Exchange Act and the related rules and regulations, nothing came to their attention that caused them to believe that the unaudited condensed consolidated financial statements do not comply as to form in all material respects with the applicable accounting requirements of the Act and the related rules and regulations adopted by the Commission;

(iv) The unaudited selected financial information with respect to the consolidated results of operations and financial position of the Company for the five most recent fiscal years included in the Prospectus and included or incorporated by reference in Item 6 of the Company’s Annual Report on Form 10-K for the most recent fiscal year agrees with the corresponding amounts (after restatement where applicable) in the audited consolidated financial statements for five such fiscal years included or incorporated by reference in the Company’s Annual Reports on Form 10-K for such fiscal years;

(v) They have compared the information in the Prospectus under selected captions with the disclosure requirements of Regulation S-K and on the basis of limited procedures specified in such letter nothing came to their attention as a result of the foregoing procedures that caused them to believe that this information does not conform in all material respects with the disclosure requirements of Items 301, 302, 402 and 503(d), respectively, of Regulation S-K;

(vi) On the basis of limited procedures, not constituting an examination in accordance with generally accepted auditing standards, consisting of a reading of the unaudited financial statements and other information referred to below, a reading of the latest available interim financial statements of the Company and its subsidiaries, inspection of the minute books of the Company and its subsidiaries since the date of the latest audited financial statements included or incorporated by reference in the Prospectus, inquiries of officials of the Company and its subsidiaries responsible for financial and accounting matters and such other inquiries and procedures as may be specified in such letter, nothing came to their attention that caused them to believe that:

(A)(i) the unaudited condensed consolidated statements of income, consolidated balance sheets and consolidated statements of cash flows included in the Prospectus and/or included or incorporated by reference in the Company’s Quarterly Reports on Form 10-Q incorporated by reference in the Prospectus do not comply as to form in all material respects with the applicable accounting requirements of the Exchange Act and the published rules and regulations adopted by the Commission, or (ii) any material modifications should be made to the unaudited condensed consolidated statements of income, consolidated balance sheets and consolidated statements of cash flows included in the Prospectus or included in the Company’s Quarterly Reports on Form 10-Q incorporated by reference in the Prospectus for them to be in conformity with generally accepted accounting principles;

(B) any other unaudited income statement data and balance sheet items included in the Prospectus do not agree with the corresponding items in the unaudited consolidated financial statements from which such data and items were derived, and any such unaudited data and items were not determined on a basis substantially consistent with the basis for the corresponding amounts in the audited consolidated financial statements included or incorporated by reference in the Company’s Annual Report on Form 10-K for the most recent fiscal year;

(C) the unaudited financial statements which were not included in the Prospectus but from which were derived the unaudited condensed financial statements referred to in clause (A) and any unaudited income statement data and balance sheet items included in the Prospectus and referred to in clause (B) were not determined on a basis substantially consistent with the basis for the audited financial statements included or incorporated by reference in the Company’s Annual Report on Form 10-K for the most recent fiscal year;

(D) as of a specified date not more than five days prior to the date of such letter, there have been any changes in the consolidated capital stock (other than issuances of capital stock upon exercise of options and stock appreciation rights, upon earn-outs of performance shares and upon conversions of convertible securities, in each case which were outstanding on the date of the latest balance sheet included or incorporated by reference in the Prospectus) or any increase in the consolidated long-term debt of the Company and its subsidiaries or other items specified by the Representatives, or any increases in any items specified by the Representatives, in each case as compared with amounts shown in the latest balance sheet included or incorporated by reference in the Prospectus, except in each case for changes, increases or decreases which the Prospectus discloses have occurred or may occur or which are described in such letter; and

(vii) In addition to the audit referred to in their report(s) included or incorporated by reference in the Prospectus and the limited procedures, inspection of minute books, inquiries and other procedures referred to in paragraphs (iii) and (vi) above, they have carried out certain specified procedures, not constituting an audit in accordance with generally accepted auditing standards, with respect to certain amounts, percentages and financial information specified by the Representatives which are derived from the general accounting records of the Company and its subsidiaries, which appear in the Prospectus (excluding documents incorporated by reference), or in Part II of, or in exhibits and schedules to, the Registration Statement specified by the Representatives or in documents incorporated by reference in the Prospectus specified by the Representatives, and have compared certain of such amounts, percentages and financial information with the accounting records of the Company and its subsidiaries and have found them to be in agreement.

All references in this Annex II to the Prospectus shall be deemed to refer to the Pricing Prospectus (including the documents incorporated by reference therein) as defined in the Underwriting Agreement as of the date of the letter delivered on the date of the Pricing Agreement for purposes of such letter and to the Prospectus (including the documents incorporated by reference therein) in relation to the applicable Designated Securities for purposes of the letter delivered at the Time of Delivery for such Designated Securities.

ANNEX III

Exhibit 99.2

[FORM OF FIXED RATE DEBENTURE]

NSTAR

4.50% DEBENTURE DUE 2019

THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF THE DEPOSITORY OR A NOMINEE THEREOF.

Unless this Security is presented by an authorized representative of The Depository Trust Company, a New York corporation (“DTC”), to NSTAR or its agent for registration of transfer, exchange, or payment, and any certificate issued is registered in the name of Cede & Co. or in such other name as is requested by an authorized representative of DTC (the “Registered Owner”)(and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein.

NSTAR, a voluntary association duly organized and validly existing under the laws of The Commonwealth of Massachusetts (herein called the “Company”, which term includes any successor corporation under the Indenture hereinafter referred to), for value received, hereby promises to pay to the Registered Owner, or registered assigns, the principal amount specified in the title of this Security (the “Principal Amount”) on the Maturity Date, except to the extent redeemed prior to the Maturity Date, and to pay interest on said principal sum semiannually on each Interest Payment Date, commencing May 15, 2010, at the rate per annum specified in the title of this Security, from the November 15 or May 15, as the case may be, next preceding the date of this Security to which interest has been paid unless the date hereof is a date to which interest has been paid, in which case from the date of this Security, or unless no interest has been paid on this Security, in which case from the date of initial issuance until payment of said principal sum has been made or duly provided for and at such rate on any overdue principal and premium and (to the extent that the payment of such interest shall be legally enforceable) on any overdue installment of interest. If any Interest Payment Date falls on a day that is not a Business Day, the interest payment will be made on the next Business Day, but will deem that payment was made on the date the payment was due. No interest will accrue on the amount payable for the period from the actual

payment date to such next Business Day. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, except as otherwise provided in said Indenture, be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the November 1 or May 1, as the case may be, next preceding such November 15 or May 15.

The principal of (and premium, if any) and interest on this Security are payable in such coin or currency of the United States of America as at the time payment is legal tender for payment of public and private debts, at the office or agency of The Bank of New York Mellon Trust Company, N.A. (hereinafter called the “Indenture Trustee,” which term includes any successor Indenture Trustee under the Indenture), as Indenture Trustee and Paying Agent, located at 222 Berkeley Street, Boston, Massachusetts 02116, or at such other office as the Indenture Trustee shall designate by written notice to the Registered Owner of this Security; provided that interest shall be paid by wire transfer in immediately available funds to an account located in the United States of America as the Registered Owner hereof shall designate to the Indenture Trustee in writing at least 15 Business Days prior to such Interest Payment Date. Any interest not punctually paid or duly provided for shall be payable as provided in the Indenture.

REFERENCE IS HEREBY MADE TO THE FURTHER PROVISIONS, INCLUDING THE OPTIONAL REDEMPTION PROVISIONS, OF THIS SECURITY SET FORTH ON THE REVERSE HEREOF, WHICH FURTHER PROVISIONS SHALL FOR ALL PURPOSES HAVE THE SAME EFFECT AS IF SET FORTH AT THIS PLACE. UNLESS THE CERTIFICATE OF AUTHENTICATION HEREON HAS BEEN EXECUTED BY THE TRUSTEE BY MANUAL SIGNATURE, THIS SECURITY SHALL NOT BE ENTITLED TO ANY BENEFIT UNDER THE INDENTURE, OR BE VALID OR OBLIGATORY FOR ANY PURPOSE.

THE NAME “NSTAR” MEANS THE TRUSTEES, AS TRUSTEES BUT NOT PERSONALLY, UNDER THE DECLARATION OF TRUST DATED APRIL 20, 1999, AS AMENDED FROM TIME TO TIME. ANY OBLIGATION, AGREEMENT, OR LIABILITY MADE, ENTERED INTO, OR INCURRED BY OR ON BEHALF OF NSTAR BINDS ONLY ITS TRUST ESTATE, AND NO SHAREHOLDER, DIRECTOR, TRUSTEE, OFFICER OR AGENT THEREOF ASSUMES OR SHALL BE HELD TO ANY LIABILITY ENTERED INTO ON BEHALF OF NSTAR.

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IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed under its seal.

INDENTURE TRUSTEE’S CERTIFICATE OF AUTHENTICATION

This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture.

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(Reverse of Security)

This Security is one of a duly authorized issue of securities of the Company (herein called the “Securities”) issued under the Indenture dated as of January 12, 2000, between the Company and The Bank of New York Mellon Trust Company, N.A. (as successor to Bank One Trust Company, N.A.), as Indenture Trustee, to which Indenture and all other indentures supplemental thereto reference is hereby made for a statement of the respective rights thereunder of the Company, the Indenture Trustee and the Holders of the Securities and the terms upon which the Securities are, and are to be, authenticated and delivered. This Security is one of the series designated as the 4.50% Debentures due 2019.

The Securities are redeemable, in whole or in part, at the Company’s option at any time. The redemption price for the Securities to be redeemed will equal the greater of the following amounts, plus, in each case, accrued interest thereon to the redemption date : (i) 100% of the principal amount of the Securities to be redeemed and (ii) as determined by the Quotation Agent (as defined herein), the sum of the present values of the remaining scheduled payments of principal and interest on the Securities to be redeemed (not including any portion of payments of interest accrued as of the redemption date) discounted to the redemption date on a semiannual basis at the Adjusted Treasury Rate (as defined herein), plus 20 basis points. The redemption price will be calculated assuming a 360-day year consisting of twelve 30-day months. The Company will mail notice of any redemption at least 30 days but not more than 60 days before the redemption date to each Holder of the Securities to be redeemed. Unless the Company defaults in payment of the redemption price, on and after the redemption date, interest will cease to accrue on the Securities or portions thereof called for redemption. The Securities will not be entitled to the benefit of a sinking fund.

The terms which follow, when used in this Security, shall have the following meanings: “Adjusted Treasury Rate” means, with respect to any redemption date, the rate per annum equal to the semiannual equivalent yield to maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such redemption date; “Comparable Treasury Issue” means the United States Treasury security selected by the Quotation Agent as having an actual or interpolated maturity comparable to the remaining term of the Securities being redeemed that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of such Securities. “Comparable Treasury Price” means, with respect to any redemption date (A) the average of the Reference Treasury Dealer Quotations for that redemption date, after excluding the highest and lowest of such Reference Treasury Dealer Quotations, or (B) if the Indenture Trustee obtains fewer than three Reference Treasury Dealer Quotations, the average of all Reference Treasury Dealer Quotations so received; “Quotation Agent” means the Reference Treasury Dealer appointed by the Company; “Reference Treasury Dealer” means (i) each of Banc of America Securities LLC and Goldman, Sachs & Co. and their respective successors, unless any of them

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ceases to be a primary U.S. Government securities dealer in New York City (a “Primary Treasury Dealer”), in which case the Company shall substitute another Primary Treasury Dealer; and (ii) any other Primary Treasury Dealer selected by the Company; and “Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any redemption date, the average, as determined by the Indenture Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Indenture Trustee by such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third business day preceding such redemption date.

As provided in the Indenture and subject to certain limitations therein set forth, the transfer of this Security may be registered on the Security Register of the Company, upon surrender of this Security for registration of transfer at the office or agency of the Indenture Trustee, as Indenture Trustee and Paying Agent, located at 222 Berkeley Street, Boston, Massachusetts 02116, or at such other office as the Indenture Trustee shall designate by written notice to the Registered Owner of this Security, duly endorsed by, or accompanied by a written instrument of transfer in form satisfactory to the Company and the Indenture Trustee duly executed by, the Registered Owner hereof or his attorney duly authorized in writing and thereupon one or more new Securities of this series, of any authorized denominations and for a like aggregate principal amount and tenor, will be issued to the designated transferee or transferees; provided, however, that the Indenture Trustee will not be required to register the transfer of or exchange any Security that has been called for redemption in whole or in part, except the unredeemed portion of Securities being redeemed in part.

The Securities of this series are issuable only in registered form without coupons in minimum denominations of $2,000 or any amount in excess thereof which is an integral multiple of $1,000. As provided in the Indenture, and subject to certain limitations therein set forth, Securities of this series are exchangeable for a like aggregate principal amount and tenor of Securities of this series of any authorized denomination, as requested by the Holder surrendering the same; provided, however, that the Company shall not be required to issue any Securities of this series of a denomination less than $1,000.

No service charge (to the Holder) will be made for any such transfer or exchange, but the Company may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith.

The Indenture Trustee shall be entitled to withhold from all payments of principal of (and premium, if any) and interest on this Security any amounts required to be withheld under the applicable provisions of the Federal income tax laws of the United States at the time of such payments.

Prior to due presentment for registration of transfer of this Security, the Company, the Indenture Trustee and any agent of the Company or the Indenture Trustee, may treat the Person in whose name this Security is registered as the owner hereof for the purpose of receiving payment as

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herein provided and for all other purposes, whether or not this Security be overdue and neither the Company, the Indenture Trustee nor any agent of the Company or Indenture Trustee shall be affected by notice to the contrary.

If an Event of Default shall occur and be continuing, the principal of the Securities of this series may be declared due and payable, and such declarations may be in certain events rescinded, in the manner and with the effect provided in the Indenture.

The Indenture permits, to the extent therein provided, the modification of the rights and obligations of the Company and the rights of the Holders of the Securities of each series to be affected under the Indenture at any time by the Company with the consent of the Holders of a majority in aggregate principal amount of the Securities at the time Outstanding if all of the Securities Outstanding are affected, or the Holders of a majority in aggregate principal amount of each series to be affected, in case one or more, but less than all, of the series of the Outstanding Securities are affected. The Indenture also contains provisions permitting the Holders of specified percentages in aggregate principal amount of the Securities of each series at the time Outstanding, on behalf of the Holders of all Securities of such series, to waive compliance by the Company with certain provisions of the Indenture and certain past defaults under the Indenture and the consequences thereof. Any such consent or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and of any Security issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Security or such other Security.

The Securities of this series are unsecured.

All terms in this Security which are defined in the Indenture shall have the meanings assigned to them in the Indenture.

No recourse shall be had for the payment of the principal of (and premium, if any), or the interest, if any, on this Security, or for any claim based thereon, or upon any obligation, covenant or agreement of the Company in the Indenture, against any partner, member, incorporator, stockholder, officer or director, as such, past, present of future, of the Company or of any successor or any of their assets, whether by virtue of any constitution, statute or rule of law or by the enforcement of any assessment of penalty or otherwise; and all such liability is expressly released and waived as a condition of, and as part of the consideration for, the issuance of this Security.

This Security shall be governed by and construed in accordance with the laws of The Commonwealth of Massachusetts.

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ABBREVIATIONS

The following abbreviations, when used in the inscription on the face of this Debenture, shall be construed as though they were written out in full according to applicable laws or regulations:

TEN COM - as tenants in common

TEN ENT - as tenants by the entireties

JT TEN - as joint tenants with right of survivorship and not as tenants in common

(State)

Additional abbreviations may also be used though not in the above list.

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ASSIGNMENT

FOR VALUE RECEIVED, I or we sell, assign and transfer to

PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE:

(Print or type name, address and zip code of assignee)

the within Security and hereby irrevocably constitute and appoint                      attorney to transfer the said Security on the books of the Company with full power of substitution in its premises.

Dated:                                                                       Signed:                                                                      

Signatures must be guaranteed by a commercial bank or trust company or a member of a major stock exchange.

Signature Guarantee

NOTICE: The above signatures of the holder(s) hereof must correspond with the name as written upon the face of the Security in every particular, without alteration or enlargement or any change whatever.

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Exhibit 99.4

NSTAR

800 Boylston Street

Boston, Massachusetts 02199

Ladies and Gentlemen:

Reference is made to our opinion dated October 9, 2009 and included as Exhibit 5.1 to the automatic shelf registration statement on Form S-3 (File No. 333-162401) (the “Registration Statement”) previously filed by NSTAR, a Massachusetts voluntary association (the “Company”), with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”), and which became effective on October 9, 2009. We are rendering this supplemental opinion in connection with the prospectus supplement dated November 12, 2009 (the “Prospectus Supplement”) filed by the Company pursuant to Rule 424 promulgated under the Securities Act. The Prospectus Supplement relates to the offering by the Company of $350,000,000 in aggregate principal amount of 4.50% Debentures due 2019 (collectively, the “Debentures”). The Debentures were issued under the Indenture dated as of January 12, 2000 between the Company and The Bank of New York Mellon Trust Company, N.A. (as successor to Bank One Trust Company, N.A.), as trustee, as supplemented by votes of the Board of Trustees of the Company dated September 24, 2009.

We have examined originals or copies, certified or otherwise identified to our satisfaction, of such documents and records and have made such investigation of fact and such examination of law as we have deemed appropriate in order to enable us to render the opinion set forth herein. In conducting such investigation, we have relied, without independent verification, upon certificates of officers of the Company, public officials and other appropriate persons.

Based upon the foregoing and subject to the additional qualifications set forth below, we are of the opinion that the Debentures have been duly authorized by all necessary corporate action of the Company and, when executed, authenticated and delivered in accordance with the terms of the Underwriting Agreement and Pricing Agreement, each dated November 12, 2009, among the Company, Banc of America Securities LLC and Goldman, Sachs & Co., as representatives for the underwriters, will constitute valid and binding obligations of the Company, subject to (i) bankruptcy, insolvency, reorganization, moratorium and other similar laws of general application affecting the rights and remedies of creditors, and (ii) general principles of equity, regardless of whether applied in proceedings in equity or at law.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the use of our name in the Registration Statement and in the Prospectus Supplement under the caption “Validity of Debentures.”