DESCRIPTION OF THE PREFERRED SECURITIES

Because this is a summary of the terms and provisions of the preferred securities and the trust agreement, it may not contain all of the information that may be important to you. You should read the entire trust agreement, including the definitions in that agreement, and the Trust Indenture Act. The form of the trust agreement is filed as an exhibit to the registration statement of which this prospectus forms a part.

General

Pursuant to the terms of the trust agreement, the administrative trustees on behalf of the trust will issue the preferred securities and the common securities. In this prospectus, we refer to the preferred securities and the common securities collectively as “trust securities.” The preferred securities will represent preferred undivided beneficial interests in the assets of the trust. The preferred securities will be entitled to a preference over the common securities in certain circumstances with respect to distributions and amounts payable on redemption or liquidation, as well as other benefits as described in the trust agreement. We will hold all of the common securities of the trust. The only assets of the trust will be the junior subordinated debentures issued by us, and the sole revenues of the trust will be payments by us under the junior subordinated debentures and the expense agreement.

The preferred securities will rank on parity with, and payments will be made on the preferred securities pro rata with, the common securities of the trust except as described under “—Subordination of Common Securities to the Preferred Securities” below. The property trustee will hold legal title to the junior subordinated debentures in trust for the benefit of the holders of the trust securities. The guarantee agreement executed by us for the benefit of the holders of the preferred securities will be a guarantee only on a subordinated basis. The guarantee agreement will not guarantee payment of distributions or amounts payable on redemption of the preferred securities or on liquidation of the preferred securities if the trust does not have funds on hand available to make such payments. See “Description of Guarantee Agreement.”

Distributions

Distributions on the preferred securities will be payable at the annual rate of [        ]% of the stated liquidation amount of $25, payable quarterly in arrears on the 15th day of January, April, July and October of each year, commencing on April 15, 2004, to the holders of preferred securities on the relevant record dates. We refer to each date on which distributions are payable in accordance with the preceding sentence as a distribution date. The amount of each distribution on the preferred securities will include amounts accrued through the date the distribution payment is due. Distributions on the preferred securities will be payable to the holders of the preferred securities as they appear on the register of the trust on the relevant record date, which will be the date 15 days prior to the relevant distribution date. Distributions will accumulate from the date of original issuance of the preferred securities.

The amount of distributions payable for any period will be computed on the basis of a 360-day year of twelve 30-day months. If any date on which distributions are payable on the preferred securities is not a business day, payment of the distribution payable on such date will be made on the next business day without any interest or other payment in respect to any such delay, with the same force and effect as if made on the date such payment was originally payable. As used in this prospectus, a “business day” means any day other than a Saturday or a Sunday, or a day on which banking institutions in the State of New York are authorized or required by law or executive order to remain closed or a day on which the corporate trust office of the property trustee or the indenture trustee is closed for business.

The funds of the trust available for distribution to you will be limited to payments by us under the junior subordinated debentures in which the trust will invest the proceeds from the issuance and sale of its preferred securities. See “Description of Junior Subordinated Debentures.” If we do not make interest payments on the

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junior subordinated debentures, the property trustee will not have funds available to pay distributions on the preferred securities. The payment of distributions, if and to the extent the trust has funds legally available for the payment of such distributions and cash sufficient to make such payments, is guaranteed by us. See “Description of Guarantee Agreement.”

Distribution Extension Periods

So long as no event of default with respect to the junior subordinated debentures has occurred and is continuing, the indenture permits us to defer the payment of interest on the junior subordinated debentures at any time or from time to time for a period not exceeding 20 consecutive quarters with respect to each such period. No extension period may extend beyond the stated maturity of the junior subordinated debentures. As a consequence of any such election, the trust will defer quarterly distributions, and distributions will not be payable, on the preferred securities during any such extension period. Distributions to which you are entitled will accumulate additional amounts thereon at the rate per annum of [        ]% thereof, compounded quarterly from the relevant distribution date, to the extent permitted under applicable law. The term “distributions” as used in this prospectus includes any such additional accumulated amounts. During any extension period, we may not and shall not allow any of our subsidiaries to:

The prohibitions in the first three bullet points above do not apply to:

Prior to the termination of any extension period, we may further extend the extension period, so long as the extension does not cause such extension period to exceed 20 consecutive quarters or extend beyond the stated maturity. If any extension period terminates and we pay all amounts then due, subject to the foregoing limitations, we may elect to begin a new extension period. Except as described in this paragraph, there is no limitation on the number of times that we may elect to begin an extension period.

We have no current intention of exercising our right to defer payments of interest by extending the interest payment period on the junior subordinated debentures.

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Redemption

Upon the repayment or redemption at any time, in whole or in part, of any junior subordinated debentures, the property trustee is required to use the proceeds from the repayment or redemption to redeem a like amount of the trust securities, upon not less than 30 nor more than 60 days’ notice of a date of redemption, at the redemption price defined below. See “Description of Junior Subordinated Debentures—Redemption.” If less than all of the junior subordinated debentures are to be repaid or redeemed on a redemption date, then the property trustee will allocate the proceeds from the repayment or redemption to the trust securities on a pro rata basis, by such method as the property trustee deems fair and appropriate, and based on liquidation amounts among the trust securities.

The “liquidation amount” is equal to the stated amount of $25 per trust security. The “redemption price” with respect to any trust security is an amount equal to the liquidation amount of such trust security, plus accumulated and unpaid distributions on the trust security to the redemption date.

Subject to Federal Reserve approval, if then required under applicable capital guidelines or policy of the Federal Reserve, we may redeem the junior subordinated debentures:

See “Description of Junior Subordinated Debentures—Redemption.”

If a tax event occurs and we do not elect to redeem the junior subordinated debentures and thereby cause a mandatory redemption of the trust securities or to liquidate the trust and cause the junior subordinated debentures to be distributed to you in liquidation of the trust, the trust securities will remain outstanding and additional sums, as described below, may be payable on the junior subordinated debentures.

For purposes of this prospectus, the term “additional sums” means the additional amounts required to be paid by us on the junior subordinated debentures in order that the amount of distributions then due and payable by the trust on the outstanding trust securities of the trust are not reduced as a result of any additional taxes, duties and other governmental charges to which the trust has become subject as a result of a tax event.

For purposes of this prospectus, a “tax event” means the receipt by us and the trust of an opinion of counsel experienced in such matters to the effect that, as a result of any amendment to, or change, including any announced prospective change, in, the laws or any regulations under such laws of the United States or any political subdivision or taxing authority thereof or therein, or as a result of any official administrative pronouncement or judicial decision interpreting or applying such laws or regulations, which amendment or change is effective or such prospective change, pronouncement or decision is announced on or after the original issuance of the preferred securities, there is more than an insubstantial risk that:

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For purposes of this prospectus, an “investment company event” means the receipt by us and the trust of an opinion of counsel experienced in such matters to the effect that, as a result of any change in law or regulation or a written change in interpretation or application of law or regulation by any legislative body, court, governmental agency or regulatory authority, there is more than an insubstantial risk that the trust is or will be considered an “investment company” that is required to be registered under the Investment Company Act of 1940, as amended, which change becomes effective on or after the original issuance of the preferred securities.

For purposes of this prospectus, a “capital treatment event” means the reasonable determination by us that, as a result of any amendment to, or change, including any prospective change, in, the laws or any regulations thereunder of the United States or any political subdivision thereof or therein, or as a result of any official or administrative pronouncement or action or judicial decision interpreting or applying such laws or regulations, which amendment or change is effective or such prospective change, pronouncement or decision is announced on or after the date of original issuance of the preferred securities, there is more than an insubstantial risk that we will not be entitled to treat the preferred securities, or any substantial portion thereof, as “Tier 1 regulatory capital” or the then equivalent thereof for purposes of the capital adequacy guidelines of the Federal Reserve, as then in effect and applicable to us. For a discussion of recent accounting changes that may impact our ability to treat the preferred securities as “Tier 1 regulatory capital,” see the section entitled “Accounting and Regulatory Treatment” above.

Redemption Procedures

The trust will redeem the preferred securities on each redemption date at the redemption price and will use the applicable proceeds from the contemporaneous redemption of the junior subordinated debentures for such redemption. The trust will redeem the preferred securities and the redemption price will be payable on each redemption date only to the extent that the trust has funds on hand available for the payment of the redemption price. See “—Subordination of Common Securities to the Preferred Securities” and “Description of Guarantee Agreement.”

If the property trustee gives a notice of redemption of the preferred securities, then, by 12:00 noon, Eastern time on the redemption date, to the extent funds are available, with respect to preferred securities held in book-entry form, the property trustee will irrevocably deposit with the depositary funds sufficient to pay the aggregate redemption price and will give the depositary irrevocable instructions and authority to pay the redemption price to you. See “Book-Entry Issuance.” If the preferred securities are no longer in book-entry form, the property trustee, to the extent funds are available, will irrevocably deposit with the paying agent for the preferred securities funds sufficient to pay the aggregate redemption price and will give such paying agent irrevocable instructions and authority to pay the redemption price to you upon surrender of your certificates evidencing your preferred securities. Notwithstanding the above, distributions payable on or prior to the redemption date for any preferred securities called for redemption will be payable to the holders of the preferred securities on the relevant record dates on the applicable distribution dates.

If the trust gives a notice of redemption and the property trustee deposits its funds as required, then upon the date of such deposit, all your rights as a holder of preferred securities called for redemption will cease, except your right to receive the applicable redemption price and any distribution payable on or prior to the redemption date, but without interest, on such redemption date, and such preferred securities will cease to be outstanding. If any date fixed for redemption of such preferred securities is not a business day, then payment of the redemption price payable on such date will be made on the next succeeding business day, without any interest or other payment in respect of any such delay. If preferred securities are called for redemption and payment of the redemption price is improperly withheld or refused and not paid either by the trust or by us under the guarantee agreement, distributions on the preferred securities will continue to accrue at the then applicable rate, from the redemption date originally established by the trust for such preferred securities to the date such redemption price is actually paid, in which case the actual payment date will be the date fixed for redemption for purposes of calculating the redemption price. See “Description of Guarantee Agreement.”

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If less than all of the trust securities issued by the trust are to be redeemed on a redemption date, then the aggregate redemption price for the trust securities being redeemed will be allocated pro rata to the preferred securities and common securities based upon the relative liquidation amounts of each class. The property trustee will select the particular preferred securities to be redeemed on a pro rata basis, based upon liquidation amounts, not more than 60 days prior to the redemption date from the outstanding preferred securities not previously called for redemption, by the method that the property trustee deems fair and appropriate and which may provide for the selection for redemption of portions (equal to $25 or an integral multiple thereof) of the liquidation amount of preferred securities. The property trustee will promptly notify the security registrar in writing of the preferred securities selected for redemption and, in the case of any preferred securities selected for partial redemption, the liquidation amount of preferred securities to be redeemed. For all purposes of the trust agreement, unless the context otherwise requires, all provisions relating to the redemption of preferred securities will relate to the portion of the aggregate liquidation amount of preferred securities which has been or is to be redeemed.

Notice of any redemption will be mailed at least 30 days but not more than 60 days before the redemption date to each holder of trust securities at such holder’s registered address.

Subject to applicable law, including, without limitation, United States federal securities law, and provided we are not then deferring interest payments on the junior subordinated debentures, we may at any time and from time to time purchase outstanding preferred securities by tender, in the open market or by private agreement.

Distribution of Junior Subordinated Debentures upon Dissolution of the Trust

We will have the right at any time to dissolve the trust and cause the junior subordinated debentures to be distributed to you in liquidation of the trust. This right is subject to our having received prior approval of the Federal Reserve if then required under applicable capital guidelines or policies of the Federal Reserve. After the liquidation date fixed for any such distribution of junior subordinated debentures for preferred securities:

We may exercise our right to dissolve the trust under circumstances where a tax event, a capital treatment event, an investment company event or other undesirable event could be avoided simply by dissolving the trust and causing the junior subordinated debentures to be distributed to you. Under the trust agreement, the trust will automatically dissolve upon expiration of its term and will earlier dissolve on the first to occur of:

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If an early dissolution occurs as described in the first, second or fourth bullet point above or upon the expiration of the trust, the trustees will liquidate the trust as quickly as they determine possible by distributing, after satisfaction of liabilities to creditors of the trust as provided by applicable law, to the holders of such trust securities a like amount of the junior subordinated debentures. For purposes of this prospectus, the term “like amount” means:

If the property trustee determines that so distributing a like amount of junior subordinated debentures is not practical, the trust will be liquidated, wound-up and terminated by the property trustee in the manner it determines. In that case, such holders will then be entitled to receive out of the assets of the trust available for distribution to holders, after satisfaction of liabilities to creditors of the trust as provided by applicable law, an amount equal to the aggregate of the liquidation amount plus accrued and unpaid distributions thereon to the date of payment. In this prospectus, we refer to such amount as the liquidation distribution.

If the liquidation distribution can be paid only in part because the trust has insufficient assets available to pay in full the aggregate liquidation distribution, then the amounts payable directly by the trust on the preferred securities will be paid on a pro rata basis, based upon liquidation amounts. The holder(s) of the common securities will be entitled to receive liquidation distributions upon any such liquidation pro rata with the holders of the preferred securities, except that if an event of default with respect to the junior subordinated debentures has occurred and is continuing, the preferred securities will have a priority over the common securities.

Under current United States federal income tax law and interpretations and assuming, as set forth in an opinion of counsel to us, that the trust is treated as a grantor trust, a distribution of the junior subordinated debentures should not be a taxable event to you. If there were a change in law, a change in legal interpretation, a tax event or other circumstances, however, the distribution could be a taxable event to the trust and to you. See “Certain Material United States Federal Income Tax Consequences.”

If we elect to dissolve the trust and thereby cause the junior subordinated debentures to be distributed to holders of the preferred securities in liquidation of the trust, we will continue to have the right to shorten the maturity of such junior subordinated debentures, subject to certain conditions. See “Description of Junior Subordinated Debentures—General.”

Subordination of Common Securities to the Preferred Securities

Except as described below, payment of distributions on, and the redemption price of, the preferred securities and common securities, as applicable, will be made pro rata based on the liquidation amounts of the preferred securities and common securities.

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If on any distribution date or redemption date an event of default with respect to the junior subordinated debentures has occurred and is continuing:

unless payment in full in cash of all accumulated and unpaid distributions, including additional amounts, if applicable, on all of the outstanding preferred securities for all distribution periods terminating on or prior thereto, or in the case of payment of the applicable redemption price, the full amount of such redemption price on all of the outstanding preferred securities then called for redemption, has been made or provided for. All funds available to the property trustee will first be applied to the payment in full in cash of all distributions on, or redemption price of, the preferred securities then due and payable, including additional amounts, if applicable.

If any event of default occurs under the trust agreement resulting from an event of default with respect to the junior subordinated debentures, we as holder of the common securities will be deemed to have waived any right to act with respect to any such event of default under the trust agreement until the effect of all such events of default with respect to the preferred securities have been cured, waived or otherwise eliminated. Until any such event of default has been so cured, waived or otherwise eliminated, the property trustee will act solely on behalf of the holders of the preferred securities and not on our behalf as holder of the common securities, and only the holders of the preferred securities will have the right to direct the property trustee to act on their behalf.

Events of Default; Notice

Any one of the following events that has occurred and is continuing constitutes an event of default under the trust agreement with respect to the preferred securities, whatever the reason for such event of default and whether it is voluntary or involuntary or arises by operation of law or pursuant to any judgment, decree or order of any court or any order, rule or regulation of any administrative or governmental body:

Within five business days after the occurrence of any event of default under the trust agreement actually known to the property trustee, the property trustee is required to transmit notice of the event of default to the holders of the trust securities, the administrative trustees and us, as depositor, unless such event of default has been cured or waived. The existence of an event of default under the trust agreement does not entitle the holders of the preferred securities to accelerate the maturity of those securities. However, in the case of an event of default with respect to the junior subordinated debentures, the property trustee and the holders of the preferred securities will have the right to accelerate the maturity of the junior subordinated debentures as described below.

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We, as depositor, and the administrative trustees are required to file annually with the property trustee a certificate as to whether or not they are in compliance with all the conditions and covenants applicable to them under the trust agreement.

If an event of default with respect to the junior subordinated debentures has occurred and is continuing, the preferred securities will have a preference over the common securities upon termination of the trust as described above. See “—Subordination of Common Securities to the Preferred Securities.” Upon an event of default with respect to the junior subordinated debentures, other than with respect to certain events in bankruptcy, insolvency or reorganization, unless the principal of all the junior subordinated debentures has already become due and payable, either the indenture trustee or the holders of not less than 25% in aggregate principal amount of the junior subordinated debentures then outstanding may declare all of the junior subordinated debentures to be due and payable immediately by giving notice in writing to us, and to the indenture trustee if notice is given by holders of the junior subordinated debentures. If the indenture trustee or the holders of not less than 25% in principal amount of the outstanding junior subordinated debentures fail to declare the principal of all of the junior subordinated debentures due and payable upon an event of default with respect to the junior subordinated debentures, the holders of at least 25% in liquidation amount of the preferred securities then outstanding will have the right to declare the junior subordinated debentures immediately due and payable. In either event, payment of principal and interest on the junior subordinated debentures remains subordinated to the extent provided in the indenture. In addition, you have the right in certain circumstances to bring a direct action against us. See “Description of Junior Subordinated Debentures—Enforcement of Certain Rights by Holders of Preferred Securities.”

If an event of default as a result of certain events in bankruptcy, insolvency or reorganization occurs with respect to the junior subordinated debentures, the junior subordinated debentures will automatically, and without any declaration or other action on the part of the indenture trustee or the holders of the junior subordinated debentures, become immediately due and payable. In such event, payment of principal and interest on the junior subordinated debentures will also remain subordinated to the extent provided in the indenture.

Removal of Trustees

Unless an event of default with respect to the junior subordinated debentures has occurred and is continuing, any of the property trustee, the Delaware trustee or the administrative trustees may be removed at any time by the holder of the common securities. For example, the holder of the common securities may seek to remove such trustees upon a substandard performance or non-performance of their duties or upon a significant increase in a trustee’s fee. If an event of default with respect to the junior subordinated debentures has occurred and is continuing, the property trustee or the Delaware trustee or both of them may be removed by the holders of a majority in liquidation amount of the outstanding preferred securities. In no event will the holders of the preferred securities have the right to vote to appoint, remove or replace the administrative trustees, which voting rights are vested exclusively in us as the holder of the common securities. No resignation or removal of a trustee and no appointment of a successor trustee will be effective until the acceptance of appointment by the successor trustee in accordance with the provisions of the trust agreement.

Co-Trustees and Separate Property Trustee

Unless an event of default under the trust agreement has occurred and is continuing, at any time or times, for the purpose of meeting the legal requirements of the Trust Indenture Act or of any jurisdiction in which any part of trust property may at the time be located, we, as the holder of the common securities, and the administrative trustees by agreed action of the majority of such trustees may appoint one or more persons either to act as a co-trustee, jointly with the property trustee, of all or any part of such trust property, or to act as separate trustee of any such property, in either case with such powers as may be provided in the instrument of appointment, and to vest in such person or persons in such capacity any property, title, right or power deemed necessary or desirable, subject to the

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provisions of the trust agreement. If we do not join in such appointment with the majority of the administrative trustees within 15 days of the receipt by us of a request from such trustees to do so, or in case an event of default with respect to the junior subordinated debentures has occurred and is continuing, the property trustee alone will have power to make such appointment.

Merger or Consolidation of Trustees

Any person into which the property trustee, the Delaware trustee or any administrative trustee that is not a natural person may be merged or converted or with which it may be consolidated, or any corporation resulting from any merger, conversion or consolidation to which such trustee is a party, or any corporation succeeding to all or substantially all the corporate trust business of such trustee, will be the successor of such trustee under the trust agreement, so long as such corporation shall be otherwise qualified and eligible.

Mergers, Consolidations, Amalgamations or Replacements of the Trust

The trust may not merge with or into, consolidate, amalgamate, or be replaced by, or convey, transfer or lease its properties and assets substantially as an entirety to any corporation or other person, except as described below. The trust may, at our request, with the consent of the administrative trustees and without the consent of the holders of the preferred securities, the property trustee or the Delaware trustee, merge with or into, consolidate, amalgamate, or be replaced by or convey, transfer or lease its properties and assets substantially as an entirety to a trust organized as such under the laws of any state if:

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Notwithstanding the foregoing, the trust shall not, except with the consent of holders of 100% in liquidation amount of the preferred securities, consolidate, amalgamate, merge with or into, or be replaced by or convey, transfer or lease its properties and assets substantially as an entirety to any other entity or permit any other entity to consolidate, amalgamate, merge with or into, or replace it if such consolidation, amalgamation, merger, replacement, conveyance, transfer or lease would cause the trust or the successor entity to be classified as other than a grantor trust for United States federal income tax purposes.

Voting Rights; Amendment of the Trust Agreement

Except as provided below and under “Description of Guarantee Agreement—Amendments and Assignment” and as otherwise required by law and the trust agreement, you will have no voting rights.

The trust agreement may be amended from time to time by us, the property trustee and the administrative trustees, without the consent of the holders of the trust securities,

Any amendments of the trust agreement will become effective when notice is given to you of the amendment.

Except as described below, the trust agreement may be amended by the administrative trustees and the property trustee with:

The consent of each affected holder of trust securities is required to amend the trust agreement to:

So long as any junior subordinated debentures are held by the property trustee, the trustees may not:

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However, where a consent under the indenture would require the consent of each holder of junior subordinated debentures affected thereby, the property trustee may not give such consent without the prior consent of each holder of the preferred securities. The trustees shall not revoke any action previously authorized or approved by a vote of the holders of the preferred securities except by subsequent vote of the required holders of the preferred securities. The property trustee shall notify each holder of the preferred securities of any notice of default received from the indenture trustee with respect to the junior subordinated debentures. In addition to obtaining the foregoing approvals of such holders of the preferred securities, prior to taking any of the foregoing actions, the trustees will obtain an opinion of counsel experienced in such matters to the effect that the trust will not be classified as other than a grantor trust for United States federal income tax purposes.

Holders of the preferred securities may give any required approval at a meeting of holders of preferred securities convened for such purpose or pursuant to written consent. The property trustee will cause a notice of any meeting at which holders of the preferred securities are entitled to vote, or of any matter upon which action by written consent of such holders is to be taken, to be given to each holder of record of the preferred securities in the manner set forth in the trust agreement.

The trust may redeem and cancel the preferred securities in accordance with the trust agreement without the vote or consent of the holders of the preferred securities.

Even though holders of the preferred securities are entitled to vote or consent under any of the circumstances described above, any of the preferred securities owned by us, the trustees or any affiliate of BancFirst Corporation or any trustees, will, for purposes of such vote or consent, be treated as if they were not outstanding.

Global Preferred Securities

The preferred securities will be represented by one or more global certificates registered in the name of the depositary, which is initially The Depository Trust Company, or its nominee. Beneficial interests in the preferred securities will be shown on, and transfers thereof will be effected only through, records maintained by participants in the depositary. Except as described below, preferred securities in certificated form will not be issued in exchange for the global certificates. See “Book-Entry Issuance.”

A global preferred security will be exchangeable for preferred securities registered in the names of persons other than the depositary or its nominee only if:

Any global security that is exchangeable pursuant to the preceding sentence will be exchangeable for definitive certificates registered in such names as the depositary directs. We expect that such instructions will be based upon directions received by the depositary with respect to ownership of beneficial interests in such global security. If preferred securities are issued in definitive form, they will be in denominations of $25 and integral multiples thereof and may be transferred or exchanged at the offices of the securities registrar described below.

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Unless and until it is exchanged in whole or in part for the individual preferred securities represented thereby, a global preferred security may not be transferred except as a whole by the depositary to a nominee of the depositary, or by a nominee of the depositary to such depositary or another nominee of such depositary, or by the depositary or any nominee to a successor depositary or any nominee of the successor depositary.

Payments on preferred securities represented by a global preferred security will be made to the depositary for the preferred securities. If preferred securities are issued in definitive form, distributions will be payable, the transfer of the preferred securities will be registrable, and preferred securities will be exchangeable for preferred securities of other denominations of a like aggregate liquidation amount, at the corporate office of the property trustee, or at the offices of any paying agent or co-paying agent appointed by the administrative trustees. However, payment of any distribution may be made at the option of the administrative trustees by check mailed to the address of the persons entitled thereto or by wire transfer. For a description of the terms of the depositary arrangements relating to payments, transfers, voting rights, redemptions and other notices and other matters, see “Book-Entry Issuance.”

Upon the issuance of a global preferred security, and the deposit of such global preferred security with or on behalf of the depositary, the depositary for such global preferred security or its nominee will credit, on its book-entry registration and transfer system, the respective aggregate liquidation amounts of the individual preferred securities represented by such global preferred securities to the accounts of participants. Such accounts will be designated by the dealers, underwriters or agents with respect to such preferred securities. Ownership of beneficial interests in a global preferred security will be limited to participants or persons that may hold interests through participants. Ownership of beneficial interests in such global preferred security will be shown on, and the transfer of that ownership will be effected only through, records maintained by the applicable depositary or its nominee, with respect to interests of participants, and the records of participants, with respect to interests of persons who hold through participants. The laws of some states require that certain purchasers of securities take physical delivery of such securities in definitive form. The limits and laws described above may impair the ability to transfer beneficial interests in a global preferred security.

So long as the depositary for a global preferred security, or its nominee, is the registered owner of such global preferred security, such depositary or such nominee, as the case may be, will be considered the sole owner or holder of the preferred securities represented by such global preferred security for all purposes under the trust agreement governing such preferred securities. Except as provided above, owners of beneficial interests in a global preferred security will not be entitled to have any of the individual preferred securities represented by such global preferred security registered in their names, will not receive or be entitled to receive physical delivery of any such preferred securities in definitive form and will not be considered the owners or holders thereof under the trust agreement.

Neither we, the property trustee, any paying agent, nor the securities registrar for such preferred securities will have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests of the global preferred security representing such preferred securities or for maintaining, supervising or reviewing any records relating to such beneficial ownership interests.

We expect that the depositary for preferred securities or its nominee, upon receipt of any payment of the liquidation amount or distributions in respect of a permanent global preferred security, immediately will credit participants’ accounts with payments in amounts proportionate to their respective beneficial interest in the aggregate liquidation amount of such global preferred security as shown on the records of such depositary or its nominee. We also expect that payments by participants to owners of beneficial interests in such global preferred security held through such participants will be governed by standing instructions and customary practices, as is now the case with securities held for the accounts of customers in bearer form or registered in “street name.” Participants will be responsible for making these payments to beneficial owners.

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Paying Agent

The paying agent for the preferred securities will initially be the property trustee and any co-paying agent chosen by the property trustee and acceptable to the administrative trustees and us. The paying agent will be permitted to resign as paying agent upon 30 days’ written notice to us and the administrative trustees and property trustee. If the property trustee is no longer the paying agent, the administrative trustees will appoint a successor, which must be a bank or trust company acceptable to the property trustee and us, to act as paying agent.

DESCRIPTION OF JUNIOR SUBORDINATED DEBENTURES

Concurrently with the issuance of the preferred securities, the trust will invest the proceeds of the issuance, together with the consideration paid by us for the common securities, in junior subordinated debentures issued by us with an aggregate principal amount of $25,773,196. The junior subordinated debentures will be issued as unsecured debt under the Junior Subordinated Indenture, dated as of                          , 2004, between us and the indenture trustee, which we refer to as the indenture. The indenture will be qualified under the Trust Indenture Act. Unless and until they are distributed to you in liquidation of the trust, all of the junior subordinated debentures issued and outstanding under the indenture will be owned by the trust.

Because this is a summary of the terms and provisions of the junior subordinated debentures and the indenture, it may not contain all of the information that is important to you. You should read the entire indenture and form of junior subordinated debenture, which are filed as exhibits to the registration statement of which this prospectus forms a part, and the Trust Indenture Act.

General

The junior subordinated debentures will bear interest at the annual rate of [        ]% of the principal amount thereof, payable quarterly in arrears on the interest payment dates, which are each 15th day of January, April, July and October of each year, commencing April 15, 2004, to the person in whose name each junior subordinated debenture is registered on the date 15 days prior to the relevant interest payment date whether or not a business day. The amount of each interest payment due on the junior subordinated debentures will include amounts accrued through the date the interest payment is due. We anticipate that, until the liquidation, if any, of the trust, each junior subordinated debenture will be held in the name of the property trustee in trust for the benefit of the holders of the preferred securities. The amount of interest payable for any period will be computed on the basis of a 360-day year of twelve 30-day months.

If any date on which interest is payable on the junior subordinated debentures is not a business day, then payment of the interest payable on that date will be made on the next business day, without any interest or other payment in respect of any such delay, in each case with the same force and effect as if made on the date such payment was originally payable. Accrued interest that is not paid on the applicable interest payment date will bear additional interest on the amount thereof, to the extent permitted by law, at [        ]% per annum, compounded quarterly. The term “interest” as used in this description includes quarterly interest payments, interest on quarterly interest payments not paid on the applicable interest payment date and additional sums, as applicable.

The junior subordinated debentures will mature on [            ], 2034. At any time, we may shorten the maturity date to any date not earlier than [five years from date of issuance], 2009. We refer to the date of maturity on the junior subordinated debentures, as it may be shortened, as the stated maturity. Subject to the prior approval of the Federal Reserve, we may exercise our right to shorten the maturity of the junior subordinated debentures under any circumstance, including to refinance the junior subordinate debentures to obtain a lower interest rate, and under circumstances where a tax event, capital treatment event, investment company event or other undesirable event could be avoided simply by shortening the maturity of the junior subordinated debentures.

If we elect to shorten the stated maturity of the junior subordinated debentures, we must give notice to the indenture trustee, and the indenture trustee must give notice of such shortening to the holders of the junior subordinated debentures no less than 60 days prior to the effectiveness of the shortened stated maturity.

The junior subordinated debentures will be unsecured and will rank junior and be subordinate in right of payment to all of our senior debt. Because we are a holding company, our right to participate in any distribution of assets of any subsidiaries upon any such subsidiaries’ liquidation or reorganization or otherwise, and thus the

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ability of holders of the preferred securities to benefit indirectly from such distribution, is subject to the prior claims of creditors of that subsidiary, except to the extent that we may ourself be recognized as a creditor of that subsidiary. Accordingly, the junior subordinated debentures will be effectively subordinated to all existing and future liabilities of our subsidiaries, and holders of junior subordinated debentures should look only to our assets for payments on the junior subordinated debentures. The indenture does not limit the incurrence or issuance of other secured or unsecured debt of ours, including senior debt, whether under the indenture or any existing or other indenture that we may enter into in the future or otherwise. See “—Subordination” below.

Option to Defer Interest Payment Period

So long as no event of default with respect to the junior subordinated debentures has occurred and is continuing, we have the right, at any time during the term of the junior subordinated debentures, to defer the payment of interest at any time or from time to time for a period not exceeding 20 consecutive quarters. No such extension period may extend beyond the stated maturity. During any extension period, we may make partial payments of interest on any interest payment date. No extension period may end other than on an interest payment date. At the end of an extension period, we must pay all interest then accrued and unpaid, together with interest on the accrued and unpaid interest at the annual rate of [        ]%, compounded quarterly, to the extent permitted by applicable law. During an extension period, interest will continue to accrue and holders of junior subordinated debentures will be required to accrue interest income for United States federal income tax purposes. See “Certain Material United States Federal Income Tax Consequences—Interest Income and Original Issue Discount.” Neither our default on any senior debt, nor a default with respect to senior debt resulting in acceleration of the maturity of that debt, constitutes an event of default with respect to the junior subordinated debentures. See “—Debenture Events of Default” below.

During any such extension period, we may not and will not permit any of our subsidiaries to:

The prohibitions in the first three bullet points above do not apply to:

Prior to the termination of any extension period, we may further extend the extension period, so long as the extension does not cause the extension period to exceed 20 consecutive quarters or extend beyond the stated maturity. Upon the termination of any extension period and the payment of all amounts then due on any interest

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payment date, we may elect to begin a new extension period subject to the above requirements. No interest will be due and payable during an extension period, except at the end of the period. We must give the property trustee, the administrative trustees and the indenture trustee notice of our election of any extension period, or an extension of such period, at least one business day prior to the earliest of:

but, in any event, not less than one business day prior to the record date. The indenture trustee will give notice of our election to begin or extend a new extension period to the holders of the preferred securities. Subject to the restrictions described above, the indenture does not limit the number of times that we may elect to begin an extension period.

Distributions on the preferred securities will be deferred by the trust during any extension period. See “Description of the Preferred Securities—Distribution Extension Periods.” For a description of certain federal income tax consequences and special considerations applicable to the junior subordinated debentures during the extension period, see “Certain Material United States Federal Income Tax Consequences.”

Additional Sums

If the trust is required to pay any additional taxes, duties or other governmental charges as a result of a tax event, we will pay as additional amounts on the junior subordinated debentures such amounts as may be required so that the distributions payable by the trust will not be reduced as a result of any such additional taxes, duties or other governmental charges. For purposes of this prospectus, these amounts are called “additional sums.”

Redemption

Subject to our having received prior approval of the Federal Reserve, if required under applicable capital guidelines or policies of the Federal Reserve, we may, at our option, redeem the junior subordinated debentures prior to maturity:

in each case at a redemption price equal to the accrued and unpaid interest on the junior subordinated debentures so redeemed to the date fixed for redemption, plus 100% of the principal amount of the junior subordinated debentures so redeemed.

Notice of any redemption will be mailed at least 30 days but not more than 60 days before the redemption date to each holder of junior subordinated debentures to be redeemed at such holder’s registered address. Unless we default in payment of the redemption price, on and after the redemption date interest ceases to accrue on such junior subordinated debentures or portions thereof called for redemption.

The junior subordinated debentures will not be subject to any sinking fund.

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Restrictions on Certain Payments

If at any time:

then we will not:

The prohibitions in the first three bullet points above do not apply to:

Debenture Events of Default

The indenture provides that any one or more of the following events constitutes an event of default with respect to the junior subordinated debentures:

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The holders of not less than a majority in aggregate outstanding principal amount of the junior subordinated debentures have the right to direct the time, method and place of conducting any proceeding for any remedy available to the indenture trustee. The indenture trustee or the holders of not less than 25% in aggregate outstanding principal amount of the junior subordinated debentures may declare the principal due and payable immediately if an event of default occurs and is continuing with respect to the junior subordinated debentures, other than an event of default with respect to certain events of bankruptcy, insolvency or reorganization for which acceleration is automatic. If the indenture trustee or such holders of such junior subordinated debentures fail to make such declaration, the holders of at least 25% in aggregate liquidation amount of the preferred securities will have that right. The holders of a majority in aggregate outstanding principal amount of the junior subordinated debentures may annul that declaration and waive the default if the default, other than the non-payment of the principal of the junior subordinated debentures which has become due solely by such acceleration, has been cured and a sum sufficient to pay all matured installments of interest and principal due otherwise than by acceleration has been deposited with the indenture trustee. If the holders of the junior subordinated debentures fail to annul that declaration and waive such default, the holders of a majority in aggregate liquidation amount of the preferred securities will have that right.

If an event of default with respect to the junior subordinated debentures with respect to certain events in bankruptcy, insolvency or reorganization occurs, the junior subordinated debentures will automatically, and without any declaration or other action on the part of the indenture trustee or the holders of the junior subordinated debentures, become immediately due and payable. In such event, payment of principal and interest on the junior subordinated debentures will also remain subordinated to the extent provided in the indenture.

The holders of a majority in aggregate outstanding principal amount of junior subordinated debentures affected thereby may, on behalf of the holders of all the junior subordinated debentures, waive any past default, except:

We are required to file annually with the indenture trustee a certificate as to whether or not we are in compliance with all the conditions and covenants applicable to us under the indenture.

Subordination

In the indenture, we have covenanted and agreed that any junior subordinated debentures issued under the indenture will be subordinate and junior in right of payment to all senior debt to the extent provided in the indenture. Upon any payment or distribution of assets to creditors upon any liquidation, dissolution, winding up, reorganization, assignment for the benefit of creditors, marshaling of assets or any bankruptcy, insolvency, or similar proceedings in connection with our insolvency or bankruptcy, the holders of senior debt will first be entitled to receive payment in full in cash, or other payment satisfactory to the holders of senior debt, of all amounts due and owing or to become due, on such senior debt before the holders of junior subordinated debentures will be entitled to receive or retain any payment in respect of the junior subordinated debentures.

If the maturity of any junior subordinated debentures is accelerated, the holders of all senior debt outstanding at the time of such acceleration will first be entitled to receive payment in full of all amounts due on the senior debt, including any amounts due upon acceleration, before the holders of junior subordinated debentures will be entitled to receive or retain any payment in respect of the junior subordinated debentures.

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No payments on account of principal or interest or premium, if any, in respect of the junior subordinated debentures may be made if a default, beyond any applicable grace period, has occurred and is continuing in any payment with respect to senior debt or an event of default with respect to any senior debt occurs and is continuing that permits the holders of the senior debt to accelerate the maturity thereof.

As a result of these subordination provisions, in the event of our bankruptcy or reorganization, holders of senior debt may receive more, ratably, and holders of the junior subordinated debentures may receive less, ratably, than our other creditors.

For purposes of this prospectus “debt” means with respect to any person, whether recourse is to all or a portion of the assets of such person and whether or not contingent:

“Senior debt” means the principal of and premium, if any, and interest, if any, including interest accruing on or after the filing of any petition in bankruptcy or for reorganization relating to us whether or not such claim for post-petition interest is allowed in such proceeding, on any of our debt, whether incurred on or prior to the date of the indenture or thereafter incurred, unless, in the instrument creating or evidencing the same or pursuant to which the same is outstanding, it is provided that such obligations are not superior in right of payment to the junior subordinated debentures or to other debt which is on parity with, or subordinated to, the junior subordinated debentures. Senior debt does not include:

As of September 30, 2003, we had approximately $4 million of senior debt outstanding and our subsidiaries had approximately $30 million of outstanding debt and other liabilities (excluding intercompany liabilities and liabilities of the type not required to be reflected on a balance sheet in accordance with generally accepted accounting principles) to which the junior subordinated debentures would have been effectively subordinated.

The indenture places no limitation on the amount of additional senior debt that may be incurred by us. We expect from time to time to incur additional indebtedness constituting senior debt.

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Denominations, Registration and Transfer

The junior subordinated debentures will be represented by global certificates registered in the name of the depositary, which will initially be The Depository Trust Company, or its nominee. Beneficial interests in the junior subordinated debentures will be shown on, and transfers thereof will be effected only through, records maintained by the depositary. Except as described below, junior subordinated debentures in certificated form will not be issued in exchange for the global certificates. See “Book-Entry Issuance.”

Unless and until a global subordinated debenture is exchanged in whole or in part for the individual junior subordinated debentures it represents, it may not be transferred except as a whole by the depositary for such global subordinated debenture to a nominee of such depositary or by a nominee of such depositary to such depositary or another nominee of such depositary or by the depositary or any nominee to a successor depositary or any nominee of such successor.

A global security will be exchangeable for junior subordinated debentures registered in the names of persons other than the depositary or its nominee only if:

Any global security that is exchangeable pursuant to the preceding sentence will be exchangeable for definitive certificates registered in such names as the depositary directs. We expect that such instructions will be based upon directions received by the depositary from its participants with respect to ownership of beneficial interests in such global security. If junior subordinated debentures are issued in definitive form, they will be in denominations of $25 and integral multiples thereof and may be transferred or exchanged at the offices described below.

If junior subordinated debentures are issued in certificated form, principal and interest will be payable, the transfer of the junior subordinated debentures will be registrable, and junior subordinated debentures will be exchangeable for junior subordinated debentures of other denominations of a like aggregate principal amount, at the corporate office of the indenture trustee, or at the offices of any paying agent or transfer agent appointed by us.

We will appoint the indenture trustee as securities registrar under the indenture. Junior subordinated debentures may be presented for exchange as provided above, and may be presented for registration of transfer, with the form of transfer endorsed thereon, or a satisfactory written instrument of transfer, duly executed, at the office of the securities registrar. We may at any time rescind the designation of any such transfer agent or approve a change in the location through which any such transfer agent acts, provided that we maintain a transfer agent in the place of payment. We may at any time designate additional transfer agents with respect to the junior subordinated debentures.

In the event of any redemption, neither we nor the indenture trustee will be required to:

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Global Subordinated Debentures

Upon the issuance of the global subordinated debenture, and the deposit of such global subordinated debenture with or on behalf of the depositary, the depositary for such global subordinated debenture or its nominee will credit, on its book-entry registration and transfer system, the respective principal amounts of the individual junior subordinated debentures represented by such global subordinated debenture to the accounts of persons that have accounts with such depositary, which are called participants. Ownership of beneficial interests in a global subordinated debenture will be limited to participants or persons that may hold interests through participants. Ownership of beneficial interests in such global subordinated debenture will be shown on, and the transfer of that ownership will be effected only through, records maintained by the applicable depositary or its nominee, with respect to interests of participants, and the records of participants, with respect to interests of persons who hold through participants. The laws of some states require that certain purchasers of securities take physical delivery of such securities in definitive form. The limits and laws described above may impair the ability to transfer beneficial interests in a global subordinated debenture.

So long as the depositary for a global subordinated debenture, or its nominee, is the registered owner of such global subordinated debenture, such depositary or such nominee, as the case may be, will be considered the sole owner or holder of the junior subordinated debentures represented by such global subordinated debenture for all purposes under the indenture governing such junior subordinated debentures. Except as provided below, owners of beneficial interests in a global subordinated debenture will not be entitled to have any of the individual junior subordinated debentures represented by such global subordinated debenture registered in their names, will not receive or be entitled to receive physical delivery of any such junior subordinated debentures in definitive form and will not be considered the owners or holders thereof under the indenture.

Payments of principal of and interest on individual junior subordinated debentures represented by a global subordinated debenture registered in the name of the depositary or its nominee will be made to the depositary or its nominee, as the case may be, as the registered owner of the global subordinated debenture representing such junior subordinated debentures. Neither we, the indenture trustee, any paying agent, nor the securities registrar for such junior subordinated debentures will have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests of the global subordinated debenture representing such junior subordinated debentures or for maintaining, supervising or reviewing any records relating to such beneficial ownership interests.

We expect that the depositary or its nominee, upon receipt of any payment of principal or interest in respect of a permanent global subordinated debenture representing the junior subordinated debentures, immediately will credit participants’ accounts with payments in amounts proportionate to their respective beneficial interest in the principal amount of the global subordinated debenture as shown on the records of such depositary or its nominee. We also expect that payments by participants to owners of beneficial interests in such global subordinated debenture held through such participants will be governed by standing instructions and customary practices, as is now the case with securities held for the accounts of customers in bearer form or registered in “street name.” Such payments will be the responsibility of such participants.

Payment and Paying Agents

Payment of principal of and any interest on the junior subordinated debentures will be made at the office of the indenture trustee, except that at our option payment of any interest may be made:

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Payment of any interest on junior subordinated debentures will be made to the person in whose name such junior subordinated debenture is registered at the close of business on the regular record date for such interest. We may at any time designate additional paying agents or rescind the designation of any paying agent. However, we will at all times be required to maintain a paying agent in each place of payment for the junior subordinated debentures. Any moneys deposited with the indenture trustee or any paying agent, or then held by us in trust, for the payment of the principal of or interest on the junior subordinated debentures and remaining unclaimed for two years after such principal or interest has become due and payable will, at our request, be repaid to us and the holder of such junior subordinated debenture may thereafter look, as a general unsecured creditor, only to us for payment thereof.

Modification of Indenture

From time to time we and the indenture trustee may, without the consent of the holders of the junior subordinated debentures, amend, waive or supplement the indenture for specified purposes, including, among other things:

The indenture permits us and the indenture trustee, with the consent of the holders of not less than a majority in principal amount of the outstanding junior subordinated debentures, to modify the indenture in a manner affecting the rights of the holders of the junior subordinated debentures. However, no such modification may, without the consent of the holder of each outstanding junior subordinated debenture affected thereby, except to the extent permitted in connection with the deferral of interest payment dates during an extension period, or the shortening of the stated maturity to a date not earlier than the first date we have a right to redeem the junior subordinated debentures:

Further, so long as any of the preferred securities remain outstanding:

without the prior consent of the holders of at least a majority of the aggregate liquidation amount of the outstanding preferred securities unless and until the principal of the junior subordinated debentures and all accrued and unpaid interest thereon have been paid in full and certain other conditions are satisfied. Where a consent under the indenture would require the consent of each holder of junior subordinated debentures, the property trustee may not give its consent without the prior consent of each holder of preferred securities.

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Enforcement of Certain Rights by Holders of Preferred Securities

If an event of default with respect to the junior subordinated debentures has occurred and is continuing and arises from our failure to pay interest or principal on the junior subordinated debentures on the date such interest or principal is otherwise payable, you may institute a legal proceeding directly against us for enforcement of payment to you of the principal of or interest on such junior subordinated debentures having a principal amount equal to the aggregate liquidation amount of your preferred securities. We refer to this proceeding in this prospectus as a “direct action.” We may not amend the indenture to remove the right to bring a direct action without the prior written consent of the holders of all of the preferred securities outstanding. If the right to bring a direct action is removed, the trust may become subject to the reporting obligations under the Exchange Act. We will have the right under the indenture to set-off any payment made by us to a holder of preferred securities in connection with a direct action.

You will not be able to exercise directly any remedies other than those set forth in the preceding paragraph available to the holders of the junior subordinated debentures unless an event of default has occurred and is continuing under the trust agreement. See “Description of the Preferred Securities—Events of Default; Notice.”

Consolidation, Merger, Sale of Assets and Other Transactions

The indenture provides that we shall not consolidate with or merge into any other person or convey, transfer or lease our properties and assets substantially as an entirety to any person, unless:

The general provisions of the indenture do not afford holders of the junior subordinated debentures protection in the event of a highly leveraged or other transaction involving us that may adversely affect holders of the junior subordinated debentures.

Satisfaction and Discharge

The indenture provides that when, among other things, all junior subordinated debentures not previously delivered to the indenture trustee for cancellation have become due and payable, will become due and payable at their stated maturity within one year, or are called for redemption within one year and we deposit or cause to be deposited with the indenture trustee trust funds, in trust, for the purpose and in an amount in the currency or currencies in which the junior subordinated debentures are payable sufficient to pay and discharge the entire indebtedness on the junior subordinated debentures not previously delivered to the indenture trustee for cancellation, for the principal and interest to the date of the deposit or to the stated maturity or redemption date, as the case may be, then the indenture will cease to be of further effect, except as to our obligations to pay all other sums due pursuant to the indenture and to provide the officers’ certificates and opinions of counsel described therein, and we will be deemed to have satisfied and discharged the indenture.

Covenants of BancFirst Corporation

We will covenant in the indenture, as to the junior subordinated debentures, that so long as no event of default with respect to the junior consolidated debenture has occurred and is continuing, if and so long as:

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then we will pay to the trust any applicable additional sums on the trust securities.

We will also covenant in the indenture:

Governing Law

The indenture and the junior subordinated debentures will be governed by and construed in accordance with the laws of the State of New York.

Information Concerning the Indenture Trustee

The indenture trustee will have and be subject to all the duties and responsibilities specified with respect to an indenture trustee under the Trust Indenture Act. Subject to such provisions, the indenture trustee is under no obligation to exercise any of the powers vested in it by the indenture at the request of any holder of junior subordinated debentures, unless offered indemnity reasonably satisfactory to it by such holder against the costs, expenses and liabilities which might be incurred thereby. The indenture trustee is not required to expend or risk its own funds or otherwise incur personal financial liability in the performance of its duties if the indenture trustee reasonably believes that repayment or adequate indemnity is not reasonably assured to it.

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BOOK-ENTRY ISSUANCE

General

The Depository Trust Company, which we refer to as DTC, will act as securities depositary for all of the preferred securities and the junior subordinated debentures. The preferred securities and the junior subordinated debentures will be issued only as fully-registered securities registered in the name of Cede & Co., DTC’s nominee. One or more fully-registered global certificates will be issued for the preferred securities and the junior subordinated debentures and will be deposited with DTC.

Each actual purchaser of the preferred securities, to whom we refer as a beneficial owner, must rely on the procedures of DTC and the participant through which such person owns its interest to exercise its rights as a holder of the preferred securities or the junior subordinated debentures.

DTC is a limited purpose trust company organized under New York banking law, a “banking organization” within the meaning of the New York banking law, a member of the Federal Reserve System, a “clearing corporation” within the meaning of the New York Uniform Commercial Code, and a “clearing agency” registered pursuant to Section 17A of the Exchange Act. DTC holds securities that its participants deposit with DTC. DTC also facilitates the settlement among participants of securities transactions, such as transfers and pledges, in deposited securities through electronic computerized book-entry changes in participants’ accounts, thereby eliminating the need for physical movement of securities certificates. Direct participants include securities brokers and dealers, banks, trust companies, clearing corporations and certain other organizations. DTC is owned by a number of its direct participants and by the New York Stock Exchange, the American Stock Exchange and the National Association of Securities Dealers, Inc. Access to the DTC system is also available to indirect participants, such as securities brokers and dealers, banks and trust companies that clear through or maintain custodial relationships with direct participants, either directly or indirectly. The rules applicable to DTC and its participants are on file with the Securities and Exchange Commission.

Purchases of preferred securities within the DTC system must be made by or through direct participants, which will receive a credit for the preferred securities on DTC’s records. The ownership interest of each actual purchaser of each preferred security (“beneficial owner”) is in turn to be recorded on the direct and indirect participants’ records. Beneficial owners will not receive written confirmation from DTC of their purchases, but beneficial owners are expected to receive written confirmations providing details of the transactions, as well as periodic statements of their holdings, from the direct or indirect participants through which the beneficial owners purchased preferred securities. Transfers of ownership interests in the preferred securities are accomplished by entries made on the books of participants acting on behalf of beneficial owners. Beneficial owners will not receive certificates representing their ownership interest in preferred securities, except if use of the book-entry-only system for the preferred securities is discontinued.

DTC will have no knowledge of the actual beneficial owners of the preferred securities. DTC’s records reflect only the identity of the direct participants to whose accounts the preferred securities are credited, which may or may not be the beneficial owners. The participants will remain responsible for keeping account of their holdings on behalf of their customers.

The information in this section concerning DTC and DTC’s book-entry system has been obtained from sources that we believe to be accurate, but we and the trust assume no responsibility for the accuracy thereof. Neither we nor the trust have any responsibility for the performance by DTC or its participants of their respective obligations as described in this prospectus or under the rules and procedures governing their respective operations.

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Notices and Voting

Conveyance of notices and other communications by DTC to direct participants, by direct participants to indirect participants, and by direct participants and indirect participants to beneficial owners and the voting rights of direct participants, indirect participants and beneficial owners will be governed by arrangements among them, subject to any statutory or regulatory requirements as may be in effect from time to time.

Redemption notices will be sent to Cede & Co. as the registered holder of the preferred securities or junior subordinated debentures. If less than all of the preferred securities or the junior subordinated debentures are being redeemed, DTC will determine by lot or pro rata the amount of the preferred securities of each direct participant to be redeemed.

Although voting with respect to the preferred securities or the junior subordinated debentures is limited to the holders of record of the preferred securities or junior subordinated debentures, as applicable, in those instances in which a vote is required, neither DTC nor Cede & Co. will itself consent or vote with respect to preferred securities or junior subordinated debentures. Under its usual procedures, DTC would mail an omnibus proxy to the relevant trustee as soon as possible after the record date. The omnibus proxy assigns Cede & Co.’s consenting or voting rights to those direct participants to whose accounts such preferred securities or junior subordinated debentures are credited on the record date, identified in a listing attached to the omnibus proxy.

Distribution of Funds

Distribution payments on the preferred securities or the junior subordinated debentures will be made by the relevant trustee to DTC. DTC’s practice is to credit direct participants’ accounts on the relevant payment date in accordance with their respective holdings shown on DTC’s records unless the depositary has reason to believe that it will not receive payments on such payment date. Payments by participants to beneficial owners will be governed by standing instructions and customary practices and will be the responsibility of such participant and not of DTC, the relevant trustee, the trust or BancFirst Corporation, subject to any statutory or regulatory requirements as may be in effect from time to time. Payment of distributions to DTC is the responsibility of the relevant trustee, disbursement of such payments to direct participants is the responsibility of DTC, and disbursements of such payments to the beneficial owners is the responsibility of direct and indirect participants.

Successor Depositaries and Termination of Book-Entry System

DTC may discontinue providing its services as securities depositary with respect to any of the preferred securities or the junior subordinated debentures at any time by giving reasonable notice to the relevant trustee and BancFirst Corporation. If a successor securities depositary is not obtained, definitive preferred securities or junior subordinated debenture certificates representing such preferred securities or junior subordinated debentures are required to be printed and delivered. We, at our option, may decide to discontinue use of the system of book-entry transfers through DTC, or a successor depositary. In either event, definitive certificates for such preferred securities or junior subordinated debentures will be printed and delivered.

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DESCRIPTION OF GUARANTEE AGREEMENT

We will enter into the guarantee agreement concurrently with the issuance of the preferred securities for the benefit of the holders of the preferred securities. The Bank of New York will act as guarantee trustee under the guarantee agreement for the purposes of compliance with the Trust Indenture Act, and the guarantee will be qualified as an indenture under the Trust Indenture Act. The guarantee trustee will hold the guarantee for the benefit of the holders of the preferred securities.

Because this is a summary of some provisions of the guarantee agreement, it may not contain all of the information that may be important to you. You should read the entire guarantee agreement, including the definitions in that agreement, and the Trust Indenture Act. The form of guarantee agreement is filed as an exhibit to the registration statement of which this prospectus forms a part.

General

We will irrevocably and unconditionally agree to pay in full on a subordinated basis, to the extent set forth in this prospectus, the guarantee payments, as such term is defined below, to the holders of the preferred securities, as and when due, regardless of any defense, right of set-off or counterclaim that the trust may have or assert other than the defense of payment. The following payments, which we refer to as the “guarantee payments,” with respect to the preferred securities, to the extent not paid or made by on behalf of the trust, will be subject to the guarantee agreement:

We may satisfy our obligation to make a guarantee payment by making direct payment of the required amounts to you or by causing the trust to pay those amounts to you.

If we do not make interest payments on the junior subordinated debentures held by the trust, the trust will not be able to pay distributions on the preferred securities and will not have funds legally available for that purpose. The guarantee agreement will rank subordinate and junior in right of payment to all of our senior debt. See “—Status of the Guarantee Agreement” below. The guarantee agreement does not limit the incurrence or issuance by us of other secured or unsecured debt, including senior debt, whether under the indenture, any other indenture that we may enter into in the future, or otherwise. We expect to incur additional indebtedness in the future, including indebtedness constituting senior debt, although we have no specific plans in this regard presently, and neither the indenture nor the trust agreement limits the amounts of the obligations that we may incur.

Because we are a bank holding company, our right to participate in any distribution of assets of any subsidiary upon the subsidiary’s liquidation or reorganization or otherwise is subject to the prior claims of the creditors of that subsidiary, except to the extent we may be recognized as a creditor of that subsidiary. Our obligations under the guarantee, therefore, will be effectively subordinated to all existing and future liabilities of our subsidiaries, and claimants should look only to our assets for payments under the guarantee.

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Status of the Guarantee Agreement

The guarantee agreement will constitute an unsecured obligation of BancFirst Corporation and will rank subordinate and junior in right of payment to all senior debt in the same manner as the junior subordinated debentures.

The guarantee agreement will constitute a guarantee of payment and not of collection. For example, the guaranteed party may institute a legal proceeding directly against us to enforce its rights under the guarantee agreement without first instituting a legal proceeding against any other person or entity. The guarantee trustee will hold the guarantee agreement for the benefit of the holders of the preferred securities. The guarantee agreement will not be discharged except by payment of the guarantee payments in full to the extent not paid by the trust or upon distribution to the holders of the preferred securities of the junior subordinated debentures.

Amendments and Assignment

Except with respect to any changes which do not adversely affect the rights of holders of the preferred securities in any material respect, in which case no vote will be required, the guarantee agreement may not be amended without the prior approval of the holders of not less than a majority of the aggregate liquidation amount of such outstanding preferred securities. All guarantees and agreements contained in the guarantee agreement shall bind our successors, assigns, receivers, trustees and representatives and shall inure to the benefit of the holders of the preferred securities then outstanding.

Events of Default

An event of default under the guarantee agreement will occur upon our default on any of our payment or other obligations under that agreement if, except with respect to a default in payment of any guarantee payments, we received notice of default and have not cured such default within 90 days of the receipt of such notice. The holders of not less than a majority in aggregate liquidation amount of the preferred securities have the right to direct the time, method and place of conducting any proceeding for any remedy available to the guarantee trustee in respect of the guarantee agreement or to direct the exercise of any trust or power conferred upon the guarantee trustee under the guarantee agreement. You may institute a legal proceeding directly against us to enforce your rights under the guarantee agreement without first instituting a legal proceeding against the trust, the guarantee trustee or any other person or entity.

As guarantor, we are required to file annually with the guarantee trustee a certificate as to whether or not we are in compliance with all the conditions and covenants applicable to it under the guarantee agreement.

Information Concerning the Guarantee Trustee

The guarantee trustee, other than during the occurrence and continuance of a default by us in performance of the guarantee agreement, undertakes to perform only those duties as are specifically set forth in the guarantee agreement. While an event of default with respect to the guarantee agreement exists, the guarantee trustee must exercise the rights and powers vested in it by the guarantee agreement and use the same degree of care and skill in exercising those rights and powers as a prudent person would exercise or use under the circumstances in the conduct of his or her own affairs. Subject to this provision, the guarantee trustee is under no obligation to exercise any of the powers vested in it by the guarantee agreement at the request of any holder of the preferred securities unless it is offered indemnity reasonably satisfactory to it against the costs, expenses and liabilities that might be incurred thereby.

Termination of the Guarantee Agreement

The guarantee agreement will terminate and be of no further force and effect upon the earliest of:

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The guarantee agreement will continue to be effective or will be reinstated, as the case may be, if at any time any holder of the preferred securities must restore payment of any sums paid under the preferred securities or the guarantee agreement.

Governing Law

The guarantee agreement will be governed by and construed in accordance with the laws of the State of New York.

EXPENSE AGREEMENT

Pursuant to the expense agreement entered into by us under the trust agreement, we will irrevocably and unconditionally guarantee to each person or entity to whom the trust becomes indebted or liable, the full payment of any costs, expenses or liabilities of the trust, including, without limitation, expenses relating to the offering of the trust securities and any expenses the property trustee may incur relating to the enforcement of the rights of the holders of the preferred securities or the junior subordinated debentures pursuant to the trust agreement and the indenture, respectively, other than obligations of the trust to pay to the holders of the preferred securities or other similar interests in the trust of the amounts due such holders pursuant to the terms of the preferred securities or such other similar interests, as the case may be. The expense agreement may be enforced against us by any person or entity to whom the trust is or becomes indebted or liable.

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RELATIONSHIP AMONG THE PREFERRED SECURITIES,

THE JUNIOR SUBORDINATED DEBENTURES AND THE GUARANTEE AGREEMENT

Full and Unconditional Guarantee

We will guarantee payments of distributions and other amounts due on the preferred securities, to the extent the trust has funds available for the payment of such distributions as and to the extent set forth under “Description of Guarantee Agreement.” Taken together, our obligations under the junior subordinated debentures, the indenture, the trust agreement, the expense agreement and the guarantee agreement provide, in the aggregate, a full, irrevocable and unconditional guarantee of payments of distributions and other amounts due on the preferred securities. No single document standing alone or operating in conjunction with fewer than all of the other documents constitutes such guarantee. It is only the combined operation of those documents that has the effect of providing a full, irrevocable and unconditional guarantee of the trust’s obligations under the preferred securities. If and to the extent that we do not make payments on the junior subordinated debentures, the trust will not pay distributions or other amounts due on the preferred securities. The guarantee agreement does not cover payment of distributions when the trust does not have sufficient funds to pay those distributions. In that event, your remedy is to institute a legal proceeding directly against us for enforcement of payment of your distributions. Our obligations under the guarantee agreement are subordinate and junior in right of payment to all senior debt.

Sufficiency of Payments

As long as payments of interest and other payments are made when due on the junior subordinated debentures, those payments will be sufficient to cover distributions and other payments due on the preferred securities, primarily because:

Notwithstanding anything to the contrary in the indenture, we have the right to set-off any payment we are otherwise required to make under the indenture to the extent we have previously made, or are concurrently on the date of such payment making, a payment under the guarantee agreement.

Enforcement Rights of Holders of the Preferred Securities Under the Guarantee Agreement

You may institute a legal proceeding directly against us to enforce your rights under the guarantee agreement without first instituting a legal proceeding against the guarantee trustee, the trust or any other person or entity.

A default or event of default under any senior debt would not constitute a default or event of default under the trust agreement. However, in the event of payment defaults under, or defaults that permit the acceleration of, senior debt, the subordination provisions of the indenture provide that no payments may be made in respect of the junior subordinated debentures until such senior debt has been paid in full or any payment default under the senior debt has been cured or waived. Failure to make required payments on the junior subordinated debentures constitutes an event of default under the trust agreement.

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Limited Purpose of the Trust

The preferred securities evidence a beneficial interest in the trust, and the trust exists for the sole purpose of issuing and selling the trust securities, using the proceeds from the sale of the trust securities to acquire the junior subordinated debentures, and engaging in only those activities necessary, advisable or incidental to the above purposes. A principal difference between the rights of a holder of the preferred securities and a holder of a junior subordinated debenture is that a holder of a junior subordinated debenture is entitled to receive from us the principal amount of and interest accrued on junior subordinated debentures held, while a holder of the preferred securities is entitled to receive distributions from the trust, or from us under the guarantee agreement, if and to the extent the trust has funds available for the payment of such distributions.

Rights Upon Dissolution

Upon any voluntary or involuntary dissolution, winding-up or liquidation of the trust involving the liquidation of the junior subordinated debentures, the holders of preferred securities will be entitled to receive, out of assets held by the trust, the liquidation distribution in cash. See “Description of the Preferred Securities—Distribution of Junior Subordinated Debentures upon Dissolution of the Trust.” Upon our voluntary or involuntary liquidation or bankruptcy, the property trustee, as holder of the junior subordinated debentures, would be a subordinated creditor of ours, subordinated in right of payment to all senior debt as set forth in the indenture, but entitled to receive payment in full of principal and interest, before any of our stockholders receive payments or distributions. Since we are the guarantor under the guarantee agreement and have agreed to pay for all costs, expenses and liabilities of the trust, other than the trust’s obligations to the holders of its preferred securities, the positions of a holder of the preferred securities and a holder of junior subordinated debentures relative to the positions of our other creditors and to our stockholders in the event of our liquidation or bankruptcy are expected to be substantially the same.

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