NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (unaudited)

(1) Mobile Mini, Inc. - Organization and Description of Business

Mobile Mini, Inc., a Delaware corporation, is a leading provider of portable storage solutions and tank and pump solutions. In these notes, the terms “Mobile Mini” the “Company,” “we,” “us,” and “our” refer to Mobile Mini, Inc.

At March 31, 2020, we had a fleet of storage solutions units operating throughout the United States (the “U.S.”), Canada and the United Kingdom (the “U.K.”), serving a diversified customer base, including construction companies, large and small retailers, medical centers, schools, utilities, distributors, the military, hotels, restaurants, entertainment complexes and households. These customers rent our products for a wide variety of applications, including the storage of construction materials and equipment, retail and manufacturing inventory, documents and records and other goods. We also have a fleet of tank and pump solutions products, concentrated in the U.S. Gulf Coast, including liquid and solid containment units, serving a specialty sector in the industry.  Our tank and pump products are rented primarily to chemical, refinery, oil and natural gas drilling, mining and environmental service customers.

Basis of Presentation and Consolidation

The consolidated financial statements include the accounts of Mobile Mini and our wholly owned subsidiaries. We do not have any subsidiaries in which we do not own 100% of the outstanding stock. All significant intercompany balances and transactions have been eliminated.  The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) applicable to interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. In the opinion of management of Mobile Mini, all adjustments (which include normal recurring adjustments) necessary to present fairly the financial position, results of operations, and cash flows for all periods presented have been made. The results of operations for the three months ended March 31, 2020 and 2019, respectively, are not necessarily indicative of the results to be expected for the full year.  

These condensed consolidated financial statements should be read in conjunction with our audited consolidated financial statements and accompanying notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019 filed with the Securities and Exchange Commission (“SEC”) on February 3, 2020.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying condensed consolidated financial statements and the notes to those statements. Actual results could differ from those estimates. Significant estimates affect the calculation of depreciation and amortization, the calculation of the allowance for doubtful accounts, the analysis of goodwill and long-lived assets for potential impairment and certain accrued liabilities.

Recent Developments – Merger Agreement

On March 1, 2020, Mobile Mini entered into a definitive merger agreement (the “Merger Agreement”) with WillScot Corporation (“WillScot”).  The Merger Agreement provides for the merger of Mobile Mini with and into a newly formed subsidiary of WillScot, with Mobile Mini surviving as a wholly owned subsidiary (the Merger”).  At the effective time of the Merger, and subject to the terms and conditions set forth in the Merger Agreement, each outstanding share of the common stock of Mobile Mini shall be converted into the right to receive 2.4050 shares of WillScot Class A common stock. The board of directors of both Mobile Mini and WillScot approved the Merger and the Merger Agreement and have recommended that their stockholders vote in favor of the adoption of the Merger Agreement.  The Merger is subject to customary closing conditions, including receipt of regulatory and stockholder approvals by the Mobile Mini and WillScot stockholders, and is expected to close in the third quarter of 2020.  In the Condensed Consolidated Statement of Income for the three months ended March 31, 2020, $15.5 million of merger-related expenses are included in the rental, selling and general expenses.

Recent Developments – COVID-19

On January 30, 2020, the World Health Organization declared an outbreak of a highly contagious form of an upper respiratory infection caused by COVID-19, a novel coronavirus strain commonly referred to as “coronavirus”.  Mobile Mini has been deemed an essential infrastructure business, which means we continue to supply our products and services in most of the areas in which we operate; however, federal and local guidelines and restrictions have significantly curtailed the level of economic activity in affected areas, which include the areas in which we conduct our business.  See additional information regarding COVID-19 in “Item 1A. Risk Factors”.

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 MOBILE MINI, INC.

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (unaudited) - Continued

(2) Impact of Recently Issued Accounting Standards

Intangibles – Goodwill and Other – Internal-Use Software.  In August 2018, the Financial Accounting Standards Board (the “FASB”) issued a standard that provides guidance on accounting for implementation costs incurred in a cloud computing arrangement that is a service contract.  The amendments in this update align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software, and hosting arrangements that include an internal-use software license.  

This guidance also requires entities to present the expense related to the capitalized implementation costs in the same line item in the statement of income as the fees associated with the hosting element (service) of the arrangement and classify payments for capitalized implementation costs in the statement of cash flows in the same manner as payments made for fees associated with the hosting element. The entity is also required to present the capitalized implementation costs in the statement of financial position in the same line item that a prepayment for the fees of the associated hosting arrangement would be presented.  This standard is effective for annual and interim periods beginning after December 15, 2019. We adopted this standard on January 1, 2020.  The adoption did not have a material effect on our consolidated financial statements.

Intangibles – Goodwill and Other.  In January 2017, the FASB issued a standard requiring an entity to no longer perform a hypothetical purchase price allocation to measure goodwill impairment.  Instead, impairment is measured using the difference between the carrying amount and the fair value of the reporting unit.  This standard is effective for annual and interim periods beginning after December 15, 2019.  We adopted this standard on January 1, 2020.  The adoption did not have a material effect on our consolidated financial statements.  

Financial Instruments – Credit Losses. In June 2016, the FASB issued guidance amending the previous guidance on impairment of financial instruments.  Among other things, the new guidance requires expectations of future credit losses to be based on relevant information from past events, including historical experience, current conditions and reasonable and supportable forecasts that affect collectability.  This guidance does not apply to receivables arising from direct rental revenue related to our operating leases.  The guidance will be effective for fiscal years and interim periods beginning after December 15, 2019.  We adopted this standard utilizing a modified-retrospective approach on January 1, 2020. The adoption did not have a material effect on our consolidated financial statements.

(3) Fair Value Measurements

Fair value is the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value is a market-based measurement determined by assumptions that market participants would use in pricing an asset or liability. We categorize each of our fair value measurements in one of the following three levels based on the lowest level of input that is significant to the fair value measurement: 

Level 1 — Observable inputs such as quoted prices in active markets for identical assets or liabilities;

Level 2 — Observable inputs, other than Level 1 inputs in active markets, that are observable either directly or indirectly; and

Level 3 — Unobservable inputs for which there is little or no market data, which require the reporting entity to develop its own assumptions.

At March 31, 2020 and December 31, 2019, we did not have any financial instruments required to be recorded at fair value on a recurring basis.

The carrying amounts of cash, cash equivalents, receivables, accounts payable and accrued liabilities approximate fair values based on their short-term nature. Based on the borrowing rates currently available to us for bank loans with similar terms and average maturities, the fair value of our revolving credit facility debt and finance leases at March 31, 2020 and December 31, 2019 approximated their respective book values.

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NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (unaudited) - Continued

The fair value of our $250.0 million aggregate principal amount of 5.875% senior notes due July 1, 2024 (the “Senior Notes” or “2024 Notes”) is based on their latest sales price at the end of each period obtained from a third-party institution and is Level 2 in the fair value hierarchy as there is not an active market for the Senior Notes.  The Senior Notes are presented on the balance sheet net of deferred financing costs. The gross carrying value and the fair value of our Senior Notes are as follows:

(4) Revenues

Revenue Recognition

A performance obligation is a promise in a contract to transfer a distinct good or service to the customer.  A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied.

Rental revenue includes revenues associated with rental contracts with customers and may have multiple performance obligations including the direct rental of fleet to our customers, fleet delivery and pickup.  Also included in rental revenues are ancillary fees including late charges and charges for damages.  For contracts with multiple performance obligations, we allocate the contract’s transaction price to each performance obligation using the contractually stated price as our best estimate of the standalone selling price of each distinct promise in the contract.  Our prices are determined using methods and assumptions developed consistently across similar customers and markets. We perform an ongoing collectability assessment of our accounts receivables and establish specific reserves when appropriate. Activity related to specific reserves is recorded as a reduction to revenue.

We enter into contracts with our customers to rent equipment based on a monthly rate for our Storage Solutions fleet and a daily, weekly or monthly rate for our Tank & Pump Solutions fleet.  Revenues from renting are recognized ratably over the rental period, in accordance with lease accounting guidance. The rental continues until cancelled by the customer or the Company. If equipment is returned prior to the end of the contractually obligated period, the excess, if any, between the amount the customer is contractually required to pay, over the cumulative amount of revenue recognized to date, is recognized as incremental revenue upon return. Customers may utilize our equipment delivery and pick-up services in conjunction with the rental of equipment, but it is not required. Revenue pursuant to the delivery or pick up of a rented unit is recognized upon completion of the service in accordance with revenue recognition guidance and is included in the rental revenues financial statement caption.

We may use third parties to satisfy our performance obligations, including both the provision of rental units and other services. To determine whether we are the principal or agent in the arrangement, we review each third-party relationship on a contract by contract basis. We are an agent when our role is to arrange for another entity to provide the rental units and other services to the customer. In these instances, we do not control the rental unit or service before it is provided. We are the principal when we control the rental unit or service prior to transferring control to the customer. Mobile Mini may be a principal in the fulfillment of some rental units and services and an agent for other rental units and services within the same contract.  We recognize revenue on a gross basis when we are the principal in the arrangement and on a net basis when we are the agent.

Sales revenue is primarily generated by the sale of new and used units, and to a lesser extent, parts and supplies sold to Tank & Pump Solutions customers.  Sales contracts generally have a single performance obligation that is satisfied at the time of delivery. Sales revenue is measured based on the consideration specified in the contract and recognized when the customer takes possession of the unit or other sale items.

Our Storage Solutions rental customers are generally billed in advance.  Additionally, we may bill our customers in advance for fleet pickup.  Tank & Pump Solutions rental customers are typically billed in arrears, a minimum of once per month.  Sales transactions are generally billed in advance or upon transfer of the sold items.  Payments from customers are generally due upon receipt of the invoice.  Certain customers have extended terms for payment, but no terms are greater than one year following the invoice date.

Taxes assessed by a governmental authority that are both imposed and concurrent with a specific revenue-producing transaction, that are collected by the Company from a customer, are excluded from revenue.

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NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (unaudited) - Continued

Contract Costs and Liabilities

When customers are billed in advance, we defer recognition of revenue and reflect unearned rental revenue at the end of the period.  As of March 31, 2020 and December 31, 2019, we had approximately $38.6 million and $41.2 million, respectively, of unearned rental revenue included in accrued liabilities in the Condensed Consolidated Balance Sheets for March 31, 2020 and December 31, 2019.  We expect to perform the remaining performance obligations and recognize the unearned rental revenue within the next twelve months.

Disaggregated Rental Revenue

In the following table, rental revenue is disaggregated by the nature of the underlying service provided and for the periods indicated.  The table also includes a reconciliation of the disaggregated rental revenue to our reportable segments.

(5) Earnings Per Share

Basic earnings per share (“EPS”) is calculated by dividing net income by the weighted average number of common shares outstanding during the period.  Restricted stock awards are subject to the risk of forfeiture and are not included in the calculation of basic weighted average number of common shares outstanding until vested. Diluted EPS is calculated under the treasury stock method.  Potential common shares include restricted common stock and incremental shares of common stock issuable upon the exercise of stock options.

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 The following table represents the effect of stock options and restricted share awards that were issued or outstanding but excluded in calculating diluted EPS because their effect would have been anti-dilutive for the period indicated, or the underlying performance criteria had not yet been met:

(6) Acquisition

During the three months ended March 31, 2020, we completed one acquisition of a portable storage business which further strengthened our business in Dallas, Texas. The accompanying condensed consolidated financial statements include the operations of the acquired business from the date of acquisition. The aggregate purchase price for the assets acquired were preliminarily allocated based on their estimated fair values at the date of the acquisition. We have not disclosed the pro-forma impact of the acquisition on operations as it was immaterial to our financial position or results of operations in aggregate.

The components of the purchase price and net assets acquired during the three months ended March 31, 2020 are as follows (in thousands):

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(8) Rental Fleet

Rental fleet is capitalized at cost and depreciated over the estimated useful life of the unit using the straight-line method. Rental fleet is depreciated whether or not it is out on rent. Capitalized cost of rental fleet includes the price paid to acquire the unit and freight charges to the location when the unit is first placed in service, and when applicable, the cost of manufacturing or remanufacturing, which includes the cost of customizing units. Ordinary repair and maintenance costs are charged to operations as incurred.

We periodically review depreciable lives and residual values against various factors, including the results of our lenders’ independent appraisal of our rental fleet, practices of our competitors in comparable industries and profit margins achieved on sales of depreciated units.  Appraisals on our rental fleet are required by our lenders on a regular basis. The appraisal typically reports no difference in the value of the unit due to the age or length of time it has been in our fleet. Based in part upon our lender’s third-party appraiser who evaluated our fleet as of August 31, 2019, management estimates that the net orderly liquidation appraisal value as of March 31, 2020 was approximately $1.0 billion.  Our net book value for this fleet as of March 31, 2020 was also $1.0 billion.

Depreciation expense related to our rental fleet for the three months ended March 31, 2020 and 2019 was $7.8 million and $7.7 million, respectively. At March 31, 2020, all rental fleet units were pledged as collateral under our Second Amended and Restated ABL Credit Agreement dated as of March 22, 2019 (the “Credit Agreement”) with Deutsche Bank AG New York Branch (“Deutsche Bank”), as administrative agent, and the other lenders party thereto.

Rental fleet consisted of the following at March 31, 2020 and December 31, 2019:

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 MOBILE MINI, INC.

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (unaudited) - Continued

(9) Property, Plant and Equipment

Property, plant and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is recorded using the straight-line method over the assets’ estimated useful lives. Our depreciation expense related to property, plant and equipment for the three months ended March 31, 2020 and 2019 was $8.2 million and $8.0 million, respectively. Normal repairs and maintenance to property, plant and equipment are expensed as incurred. When property or equipment is retired or sold, the net book value of the asset, reduced by any proceeds, is charged to gain or loss on the disposal of property, plant and equipment and is included in rental, selling and general expenses in the Condensed Consolidated Statements of Income.

Property, plant and equipment at March 31, 2020 and December 31, 2019 consisted of the following:

(10) Goodwill and Intangibles

For acquired businesses, we record assets acquired and liabilities assumed at their estimated fair values on the respective acquisition dates. Based on these values, the excess purchase prices over the fair value of the net assets acquired is recorded as goodwill. Of the $710.1 million total goodwill at March 31, 2020, $474.8 million related to the North America Storage Solutions segment, $54.0 million related to the U.K. Storage Solutions segment and $181.2 million related to the Tank & Pump Solutions segment.

The following table shows the activity and balances related to goodwill from January 1, 2020 to March 31, 2020 (in thousands): 

Intangible assets are amortized over the estimated useful life of the asset utilizing a method which reflects the estimated pattern in which the economic benefits will be consumed.  Customer relationships are amortized based on the estimated attrition rates of the underlying customer base. Other intangibles are amortized using the straight-line method.  When the intangible reaches the end of its life and no longer has value to the Company, the gross carrying amount and the related accumulated amortization is removed from our balance sheet.

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Amortization expense for amortizable intangibles was approximately $1.5 million and $1.6 million for the three-month periods ended March 31, 2020 and 2019, respectively.  Based on the carrying value at March 31, 2020, future amortization of intangible assets is expected to be as follows for the years ended December 31 (in thousands): 

(11) Debt

Lines of Credit

On March 22, 2019, Mobile Mini and certain of its subsidiaries entered into the Second Amended and Restated ABL Credit Agreement dated as of March 22, 2019 (the “Credit Agreement”) with Deutsche Bank AG New York Branch (“Deutsche Bank”), as administrative agent, and the other lenders party thereto. The Credit Agreement provides for a $1 billion first lien senior secured revolving credit facility, which is for borrowing in U.S. Dollars (the “U.S. Subfacility”), in British Pounds and Euros (the “U.K. Subfacility”), and in Canadian Dollars (the “Canadian Subfacility”). The U.S. Subfacility is subject to, among other things, the terms of a borrowing base calculated as a discount to the value of certain pledged U.S. collateral; the U.K. Subfacility is subject to a similar borrowing base that includes certain pledged U.K. collateral; and the Canadian Subfacility is subject to a similar borrowing base that includes certain pledged Canadian collateral.  Under the terms of the Credit Agreement, certain real property will require an appraisal before the value can be considered in the borrowing base of the respective subfacilities. All three borrowing bases are subject to certain reserves and caps customary for financings of this type. The Credit Agreement has an accordion feature that permits, under certain conditions, an increase of up to $500 million of additional commitments. If at any time the aggregate amounts outstanding under the subfacilities exceed the respective borrowing base then in effect, a prepayment of an amount sufficient to eliminate such excess is required to be made. Mobile Mini has the right to prepay loans under the Credit Agreement in whole or in part at any time.  All amounts borrowed under the Credit Agreement must be repaid on or before March 22, 2024.  The Credit Agreement also provides for the issuance of irrevocable standby letters of credit by U.S. lenders in amounts totaling up to $50 million, by U.K.-based lenders in amounts totaling up to $20 million and by Canadian-based lenders in amounts totaling up to $20 million.

Loans made under the (i) U.S. Subfacility bear interest at a rate equal to, at Mobile Mini’s option, either (a) the London interbank offered rate (“LIBOR”) plus an applicable margin (“LIBOR Loans”) or (b) the prime rate plus an applicable margin (“Base Rate Loans”);  (ii) U.K. Subfacility denominated in British Pounds bear interest at LIBOR plus an applicable margin and loans denominated in Euros bear interest at the Euro interbank offered rate plus an applicable margin; and (iii) Canadian Subfacility bear interest at a rate equal to, at Mobile Mini’s option, either (a) the Canadian prime rate plus an applicable margin  or (b) the Canadian Dollar bankers’ acceptance rate  plus an applicable margin.  As of March 31, 2020, the applicable margins are 1.50% for LIBOR Loans and 0.50% for Base Rate Loans.  Mobile Mini is also required to pay an unused line fee in respect of the unutilized commitments under the Credit Agreement at a fee rate of 0.225% per annum, as well as customary letter of credit fees.

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 MOBILE MINI, INC.

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (unaudited) - Continued

Ongoing extensions of credit under the Credit Agreement are subject to customary conditions, including sufficient availability under the respective borrowing base.  The Credit Agreement also contains various financial and nonfinancial covenants which require Mobile Mini to, among other things, comply with a minimum fixed charge coverage ratio of 1.00 to 1.00 as of the last day of each quarter, upon specified excess availability under the Credit Agreement falling below the greater of (y) $90 million and (z) 10% of the lesser of the then total revolving loan commitment and aggregate borrowing base.  As of March 31, 2020, we were in compliance with the minimum borrowing availability threshold set forth in the Credit Agreement and therefore, are not subject to any financial maintenance covenants.

The U.S. Subfacility is guaranteed by Mobile Mini and certain of its domestic subsidiaries.  The U.K. Subfacility and the Canadian Subfacility are guaranteed by Mobile Mini and certain of its domestic and foreign subsidiaries.  The U.S. Subfacility is secured by a first priority lien on substantially all assets of Mobile Mini and the guarantors of such subfacility.  The U.K. and Canadian Subfacilities are secured by a first priority lien on substantially all of the assets of the borrowers and the guarantors of such subfacilities.  

The Credit Agreement also includes other covenants, representations, warranties, indemnities, and events of default that are customary for facilities of this type, including events of default relating to a change of control of Mobile Mini.

Senior Notes

We have outstanding $250.0 million aggregate principal amount of 2024 Notes issued at their face value on May 9, 2016.  The 2024 Notes bear interest at a rate of 5.875% per year and mature on July 1, 2024. Interest on the 2024 Notes is payable semiannually in arrears on January 1 and July 1. The 2024 Notes are senior unsecured obligations of the Company and are unconditionally guaranteed on a senior unsecured basis by certain of our existing and future domestic subsidiaries.

Obligations Under Finance Leases

At March 31, 2020 and December 31, 2019, obligations under finance leases for certain real property and transportation related equipment were $75.5 million and $74.4 million, respectively.  See additional information in Note 12.

(12) Leases

Real Estate

We lease our corporate and administrative offices in Phoenix, Arizona and our U.K. headquarters in Stockton-on-Tees.  We also lease field locations throughout the U.S. and the U.K., as well as two in Canada.  Many real estate leases include one or more options to renew.  The exercise of lease renewal options is generally at our discretion and we assess the initial lease term based on the term that we are reasonably certain to occupy the leased property.  None of our real estate leases contain residual value guarantees or purchase options.  The majority of our real estate leases are operating leases.  

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 MOBILE MINI, INC.

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (unaudited) - Continued

Equipment Leases

Mobile Mini also engages in leases related to ancillary equipment to support our field operations; such as, forklifts, trucks, service vehicles and automobiles.  These leases often include an option to purchase the equipment at the end of the lease and are generally finance leases.  In addition, we have leases for certain office equipment.  

Lease Assets and Liabilities

For leases with an initial term greater than twelve months, we recognize a lease asset and liability at commencement date.  Lease assets are initially measured at cost, which includes the initial amount of the lease liability, plus any initial direct costs incurred, less lease incentives received.  In our Condensed Consolidated Balance Sheets, finance lease assets are included in property, plant and equipment.  For operating leases, the liability is initially and subsequently measured as the present value of the unpaid lease payments.  For finance lease liabilities, the lease liability is also initially measured as the present value of the unpaid lease payments and is subsequently measured at amortized cost using the effective interest method.  We are required to use estimates and judgments in the determination of our lease liabilities.  

(13) Income Taxes

We are subject to taxation in the U.S. federal jurisdiction, as well as various U.S. state and foreign jurisdictions. We have identified our U.S. federal tax return as our “major” tax jurisdiction. As of March 31, 2020, we are no longer subject to examination by U.S. federal tax authorities for years prior to 2016, to examination for any U.S. state taxing authority prior to 2014, or to examination for any foreign jurisdictions prior to 2015. All subsequent periods remain open to examination.

Our effective income tax rate increased to 44.4% for the three months ended March 31, 2020, compared to 26.5% for the prior-year period. The increase in the effective tax rate was primarily due to non-deductible costs incurred during the quarter related to our proposed merger with WillScot.  

Uncertain tax positions are recognized and measured using a two-step approach. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation process, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon ultimate settlement.

As of March 31, 2020, the Company had $0.5 million of unrecognized tax benefits, all of which would affect the effective tax rate if recognized. A reconciliation of the beginning and ending balance of unrecognized tax benefits is as follows:

All of the unrecognized tax benefits outstanding at March 31, 2020 are expected to reverse within the next twelve months.

Our policy for recording interest and penalties associated with audits is to record such items as a component of income before taxes. Penalties and associated interest costs, if any, are recorded in rental, selling and general expenses in our Condensed Consolidated Statements of Income.

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 MOBILE MINI, INC.

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (unaudited) - Continued

(14) Share-Based Compensation

We have historically awarded stock options and restricted stock awards for employees and non-employee directors as a means of attracting and retaining quality personnel and to align employee performance with stockholder value.  Share-based compensation plans are approved by our stockholders and administered by the stock compensation committee of the Company’s Board of Directors (the “Board”). The current plan allows for a variety of equity programs designed to provide flexibility in implementing equity and cash awards, including incentive stock options, nonqualified stock options, restricted stock awards, restricted stock units, stock appreciation rights, performance stock, performance units and other stock-based awards. Participants may be granted any one of the equity awards or any combination. We do not award stock options with an exercise price below the market price of the underlying securities on the date of grant.  As of March 31, 2020, 0.8 million shares are available for future grants, assuming performance-based awards vest at their target amount.  Generally, stock options have contractual terms of ten years.

Service-based awards. We grant share-based compensation awards that vest over time subject to the employee rendering service over the vesting period.  The majority of the service–based awards vest in equal annual installments over a period of three to four years. The expense for service-based awards is expensed ratably over the full service period of the grant.

Performance-based awards. All performance-based awards granted from 2017 through 2020 vest contingently over a three-year period assuming a target number of options or restricted share awards.  However, the terms of these awards provide that the number of options or restricted share awards that ultimately vest may vary between 50% and 200% of the target amount or may be zero.  The targets were set at the time of grant.  For awards granted from 2017 through 2020, performance conditions are related to the Company’s return on capital employed.

Expense related to performance-based awards that have multiple vesting dates is recognized using the accelerated attribution approach, whereby each vesting tranche is treated as a separate award for purposes of determining the implicit service period.  The accelerated attribution approach generally results in a higher expense during the earlier years of vesting.  Expense related to performance-based awards is recognized based upon anticipated attainment.  All share-based compensation was included in rental, selling and general expenses for the three months ended March 31, 2020 and 2019.

As of March 31, 2020, the Company did not have any unvested stock options.  As of March 31, 2020, the unrecognized compensation cost related to restricted stock awards assuming achievement at target was approximately $13.2 million, which is expected to be recognized over a weighted-average period of approximately 1.8 years.

Stock Options. No new stock option grants were made in the three months ended March 31, 2020 and there are no unvested stock options as of March 31, 2020.

The following table summarizes stock option activity for the three months ended March 31, 2020:

Due to actual performance exceeding targets, shares granted in 2017 that contingently vested based upon 2019 performance criteria vested above target at 200% resulting in additional awards.

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The aggregate intrinsic value of options exercised during the three months ended March 31, 2020 was approximately $0.3 million.

Restricted Stock Awards. The fair value of restricted stock awards is estimated as the closing price of our common stock on the date of grant. A summary of restricted stock award activity for the three months ended March 31, 2020 is as follows: