Significant Accounting Policies

Principles of Consolidation

The consolidated financial statements include our accounts and those of our subsidiaries, which are wholly-owned or controlled by us. Entities which we do not control through our voting interest and entities which are variable interest entities, but where we are not the primary beneficiary, are accounted for under the equity method. See Note 5, "Debt and Preferred Equity Investments" and Note 6, "Investments in Unconsolidated Joint Ventures." All significant intercompany balances and transactions have been eliminated.

We consolidate a variable interest entity, or VIE, in which we are considered the primary beneficiary. The primary beneficiary is the entity that has (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE.

A noncontrolling interest in a consolidated subsidiary is defined as the portion of the equity (net assets) in a subsidiary not attributable, directly or indirectly, to us. Noncontrolling interests are required to be presented as a separate component of equity in the consolidated balance sheet and the presentation of net income is modified to present earnings and other comprehensive income attributed to controlling and noncontrolling interests.

We assess the accounting treatment for each joint venture and debt and preferred equity investment. This assessment includes a review of each joint venture or limited liability company agreement to determine the rights provided to each party and whether those rights are protective or participating. For all VIEs, we review such agreements in order to determine which party has the power to direct the activities that most significantly impact the entity's economic performance. In situations where we and our partner approve, among other things, the annual budget, receive a detailed monthly reporting package, meet on a quarterly basis to review the results of the joint venture, review and approve the joint venture's tax return before filing, and approve all leases that cover more than a nominal amount of space relative to the total rentable space at each property, we do not consolidate the joint venture as we consider these to be substantive participation rights that result in shared power of the activities that most significantly impact the performance of the joint venture. Our joint venture agreements typically contain certain protective rights such as requiring partner approval to sell, finance or refinance the property and the payment of capital expenditures and operating expenditures outside of the approved budget or operating plan.

In January 2018, the partnership agreement for our investment in the property at 919 Third Avenue was modified resulting in our partner now having substantive participating rights in the venture. As a result the investment will no longer be deemed a VIE and our investment in the property will be deconsolidated as of January 1, 2018. The Company will record its non-controlling interest at fair value. This fair value will be allocated to the assets and liabilities, including identified intangibles. Under this methodology, the leases are ascribed an in-place lease intangible value as well as an above or below market lease intangible value which will be amortized over the remaining term of the associated leases.

Investment in Commercial Real Estate Properties

Real estate properties are presented at cost less accumulated depreciation and amortization. Costs directly related to the development or redevelopment of properties are capitalized. Ordinary repairs and maintenance are expensed as incurred; major replacements and betterments, which improve or extend the life of the asset, are capitalized and depreciated over their estimated useful lives.

We recognize the assets acquired, liabilities assumed (including contingencies) and any noncontrolling interests in an acquired entity at their respective fair values on the acquisition date. When we acquire our partner's equity interest in an existing unconsolidated joint venture and gain control over the investment, we record the consolidated investment at fair value. The difference between the book value of our equity investment on the purchase date and our share of the fair value of the investment's purchase price is recorded as a purchase price fair value adjustment in our consolidated statements of operations. See Note 3, "Property Acquisitions."

We allocate the purchase price of real estate to land and building (inclusive of tenant improvements) and, if determined to be material, intangibles, such as the value of above- and below-market leases and origination costs associated with the in-place leases. We depreciate the amount allocated to building (inclusive of tenant improvements) over their estimated useful lives, which generally range from three to 40 years. We amortize the amount allocated to the above- and below-market leases over the remaining term of the associated lease, which generally range from one to 14 years, and record it as either an increase (in the case of below-market leases) or a decrease (in the case of above-market leases) to rental income. We amortize the amount allocated to the values associated with in-place leases over the expected term of the associated lease, which generally ranges from one to 14 years. If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off. The tenant improvements and origination costs are amortized as an expense over the remaining life of the lease (or charged against earnings if the lease is terminated prior to its contractual expiration date). We assess fair value of the leases based on estimated cash flow projections that utilize appropriate discount and capitalization rates and available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known trends, and market/economic conditions that may affect the property. To the extent acquired leases contain fixed rate renewal options that are below-market and determined to be material, we amortize such below-market lease value into rental income over the renewal period. As of December 31, 2017, the weighted average amortization period for above-market leases, below-market leases, and in-place lease costs is 6.0 years, 23.3 years, and 16.3 years, respectively.

We incur a variety of costs in the development and leasing of our properties. After the determination is made to capitalize a cost, it is allocated to the specific component of a project that is benefited. Determination of when a development project is substantially complete and capitalization must cease involves a degree of judgment. The costs of land and building under development include specifically identifiable costs. The capitalized costs include, but are not limited to, pre-construction costs essential to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. We consider a construction project as substantially completed and held available for occupancy upon the completion of tenant improvements, but no later than one year after major construction activity ceases. We cease capitalization on the portions substantially completed and occupied or held available for occupancy, and capitalize only those costs associated with the portions under construction.

Properties are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows:



Category		Term
Building (fee ownership)		40 years
Building improvements		shorter of remaining life of the building or useful life
Building (leasehold interest)		lesser of 40 years or remaining term of the lease
Property under capital lease		remaining lease term
Furniture and fixtures		four to seven years
Tenant improvements		shorter of remaining term of the lease or useful life

Depreciation expense (including amortization of capital lease assets) totaled $365.3 million, $783.5 million, and $523.8 million for the years ended December 31, 2017, 2016 and 2015, respectively.

On a periodic basis, we assess whether there are any indications that the value of our real estate properties may be other than temporarily impaired or that their carrying value may not be recoverable. A property's value is considered impaired if management's estimate of the aggregate future cash flows (undiscounted) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the loss will be measured as the excess of the carrying amount of the property over the calculated fair value of the property.

We also evaluate our real estate properties for impairment when a property has been classified as held for sale. Real estate assets held for sale are valued at the lower of their carrying value or fair value less costs to sell and depreciation expense is no longer recorded. See Note 4, "Properties Held for Sale and Dispositions."

Cash and Cash Equivalents

We consider all highly liquid investments with maturity of three months or less when purchased to be cash equivalents.

Restricted Cash

Restricted cash primarily consists of security deposits held on behalf of our tenants, interest reserves, as well as capital improvement and real estate tax escrows required under certain loan agreements.

Fair Value Measurements

See Note 16, "Fair Value Measurements."

Investment in Marketable Securities

At acquisition, we designate a security as held-to-maturity, available-for-sale, or trading. As of December 31, 2017, we did not have any securities designated as held-to-maturity or trading. We account for our available-for-sale securities at fair value pursuant to Accounting Standards Codification, or ASC, 820-10, with the net unrealized gains or losses reported as a component of accumulated other comprehensive income or loss. Any unrealized losses that are determined to be other-than-temporary are recognized in earnings up to their credit component.

The cost of bonds and marketable securities sold is determined using the specific identification method.

At December 31, 2017 and 2016, we held the following marketable securities (in thousands):



	December 31,
	2017		2016
Equity marketable securities	$	—	$	48,315
Commercial mortgage-backed securities	28,579		36,795
Total marketable securities available-for-sale	$	28,579	$	85,110

The cost basis of the commercial mortgage-backed securities was $27.5 million and $36.0 million at December 31, 2017 and 2016, respectively. These securities mature at various times through 2035. We held no equity marketable securities as of December 31, 2017. The cost basis of the equity marketable securities was $43.3 million at December 31, 2016.

During the year ended December 31, 2017, we disposed of marketable securities for aggregate net proceeds of $55.1 million and realized a gain of $3.3 million, which is included in gain (loss) on sale of investment in marketable securities on the consolidated statements of operations.

During the year ended December 31, 2016, we disposed of marketable securities for aggregate net proceeds of $7.0 million and realized a loss of $0.1 million, which is included in gain (loss) on sale of investment in marketable securities on the consolidated statements of operations.

Investments in Unconsolidated Joint Ventures

We account for our investments in unconsolidated joint ventures under the equity method of accounting in cases where we exercise significant influence over, but do not control, these entities and are not considered to be the primary beneficiary. We consolidate those joint ventures that we control or which are VIEs and where we are considered to be the primary beneficiary. In all these joint ventures, the rights of the joint venture partner are both protective as well as participating. Unless we are determined to be the primary beneficiary in a VIE, these participating rights preclude us from consolidating these VIE entities. These investments are recorded initially at cost, as investments in unconsolidated joint ventures, and subsequently adjusted for equity in net income (loss) and cash contributions and distributions. Equity in net income (loss) from unconsolidated joint ventures is allocated based on our ownership or economic interest in each joint venture. When a capital event (as defined in each joint venture agreement) such as a refinancing occurs, if return thresholds are met, future equity income will be allocated at our increased economic interest. We recognize incentive income from unconsolidated real estate joint ventures as income to the extent it is earned and not subject to a clawback feature. Distributions we receive from unconsolidated real estate joint ventures in excess of our basis in the investment are recorded as offsets to our investment balance if we remain liable for future obligations of the joint venture or may otherwise be committed to provide future additional financial support. None of the joint venture debt is recourse to us. The Company has performance guarantees under master leases at two joint ventures. See Note 6, "Investments in Unconsolidated Joint Ventures."

We assess our investments in unconsolidated joint ventures for recoverability, and if it is determined that a loss in value of the investment is other than temporary, we write down the investment to its fair value. We evaluate our equity investments for impairment based on the joint ventures' projected discounted cash flows. We do not believe that the values of any of our equity investments were impaired at December 31, 2017.

We may originate loans for real estate acquisition, development and construction, where we expect to receive some of the residual profit from such projects. When the risk and rewards of these arrangements are essentially the same as an investor or joint venture partner, we account for these arrangements as real estate investments under the equity method of accounting for investments. Otherwise, we account for these arrangements consistent with the accounting for our debt and preferred equity investments.

Deferred Lease Costs

Deferred lease costs consist of fees and direct costs incurred to execute operating leases and are amortized on a straight-line basis over the related lease term. Certain of our employees provide leasing services to the wholly-owned properties. For the years ended December 31, 2017, 2016 and 2015, $16.4 million, $15.4 million, and $15.4 million of their compensation, respectively, was capitalized and is amortized over an estimated average lease term of seven years.

Deferred Financing Costs

Deferred financing costs represent commitment fees, legal, title and other third party costs associated with obtaining commitments for financing which result in a closing of such financing. These costs are amortized over the terms of the respective agreements. Unamortized deferred financing costs are expensed when the associated debt is refinanced or repaid before maturity. Costs incurred in seeking financing transactions, which do not close, are expensed in the period in which it is determined that the financing will not close. Deferred debt issuance costs related to a recognized debt liability are presented in the balance sheet as a direct deduction from the carrying amount of that debt liability.

Revenue Recognition

Rental revenue is recognized on a straight-line basis over the term of the lease. Rental revenue recognition commences when the tenant takes possession or controls the physical use of the leased space. In order for the tenant to take possession, the leased space must be substantially ready for its intended use. To determine whether the leased space is substantially ready for its intended use, management evaluates whether we are or the tenant is the owner of tenant improvements for accounting purposes. When management concludes that we are the owner of tenant improvements, rental revenue recognition begins when the tenant takes possession of the finished space, which is when such tenant improvements are substantially complete. In certain instances, when management concludes that we are not the owner (the tenant is the owner) of tenant improvements, rental revenue recognition begins when the tenant takes possession of or controls the space. When management concludes that we are the owner of tenant improvements for accounting purposes, we record amounts funded to construct the tenant improvements as a capital asset. For these tenant improvements, we record amounts reimbursed by tenants as a reduction of the capital asset. When management concludes that the tenant is the owner of tenant improvements for accounting purposes, we record our contribution towards those improvements as a lease incentive, which is included in deferred costs, net on our consolidated balance sheets and amortized as a reduction to rental revenue on a straight-line basis over the term of the lease. The excess of rents recognized over amounts contractually due pursuant to the underlying leases are included in deferred rents receivable on the consolidated balance sheets. We establish, on a current basis, an allowance for future potential tenant credit losses, which may occur against this account. The balance reflected on the consolidated balance sheets is net of such allowance.

In addition to base rent, our tenants also generally will pay their pro rata share of increases in real estate taxes and operating expenses for the building over a base year. In some leases, in lieu of paying additional rent based upon increases in building operating expenses, the tenant will pay additional rent based upon increases in the wage rate paid to porters over the porters' wage rate in effect during a base year or increases in the consumer price index over the index value in effect during a base year. In addition, many of our leases contain fixed percentage increases over the base rent to cover escalations. Electricity is most often supplied by the landlord either on a sub-metered basis, or rent inclusion basis (i.e., a fixed fee is included in the rent for electricity, which amount may increase based upon increases in electricity rates or increases in electrical usage by the tenant). Base building services other than electricity (such as heat, air conditioning and freight elevator service during business hours, and base building cleaning) are typically provided at no additional cost, with the tenant paying additional rent only for services which exceed base building services or for services which are provided outside normal business hours. These escalations are based on actual expenses incurred in the prior calendar year. If the expenses in the current year are different from those in the prior year, then during the current year, the escalations will be adjusted to reflect the actual expenses for the current year.

We recognized $20.3 million, $196.2 million, and $38.7 million of rental revenue for the years ended December 31, 2017, 2016, and 2015 respectively, for the amortization of aggregate below-market leases in excess of above-market leases and a reduction in lease origination costs, resulting from the allocation of the purchase price of the applicable properties. Included in rental revenue for the year ended December 31, 2016 is $172.4 million related to the amortization of below-market leases at 388-390 Greenwich Street as a result of the tenant exercising their option to purchase the property and entering into an agreement to accelerate the sale.

We recognized as a reduction to interest expense the amortization of the above-market rate mortgages assumed of $0.8 million, $2.8 million, and $2.3 million for the years ended December 31, 2017, 2016 and 2015, respectively.

The following summarizes our identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases) as of December 31, 2017 and 2016 (in thousands):



	December 31,
	2017			2016
Identified intangible assets (included in other assets):
Gross amount	$	325,880		$	651,099
Accumulated amortization	(277,038		)	(410,930		)
Net⁽¹⁾	$	48,842		$	240,169
Identified intangible liabilities (included in deferred revenue):
Gross amount	$	540,283		$	655,930
Accumulated amortization	(402,583		)	(464,749		)
Net⁽¹⁾	$	137,700		$	191,181


(1)	As of December 31, 2017, $13.9 million net intangible assets and $4.1 million net intangible liabilities were reclassified to assets held for sale and liabilities related to assets held for sale.

The estimated annual amortization of acquired above-market leases, net of acquired (below-market) leases (a component of rental revenue), for each of the five succeeding years is as follows (in thousands):



2018	$	(13,853	)
2019	(13,250		)
2020	(12,432		)
2021	(3,950		)
2022	(3,647		)

The estimated annual amortization of all other identifiable assets (a component of depreciation and amortization expense) including tenant improvements for each of the five succeeding years is as follows (in thousands):



2018	$	9,700
2019	7,716
2020	6,783
2021	3,927
2022	2,365

We record a gain on sale of real estate when title is conveyed to the buyer, subject to the buyer's financial commitment being sufficient to provide economic substance to the sale and provided that we have no substantial economic involvement with the buyer.

Interest income on debt and preferred equity investments is accrued based on the contractual terms of the instruments and when, in the opinion of management, it is deemed collectible. Some debt and preferred equity investments provide for accrual of interest at specified rates, which differ from current payment terms. Interest is recognized on such loans at the accrual rate subject to management's determination that accrued interest is ultimately collectible, based on the underlying collateral and operations of the borrower. If management cannot make this determination, interest income above the current pay rate is recognized only upon actual receipt.

Deferred origination fees, original issue discounts and loan origination costs, if any, are recognized as an adjustment to interest income over the terms of the related investments using the effective interest method. Fees received in connection with loan commitments are also deferred until the loan is funded and are then recognized over the term of the loan as an adjustment to yield. Discounts or premiums associated with the purchase of loans are amortized or accreted into interest income as a yield adjustment on the effective interest method based on expected cash flows through the expected maturity date of the related investment. If we purchase a debt or preferred equity investment at a discount, intend to hold it until maturity and expect to recover the full value of the investment, we accrete the discount into income as an adjustment to yield over the term of the investment. If we purchase a debt or preferred equity investment at a discount with the intention of foreclosing on the collateral, we do not accrete the discount. For debt investments acquired at a discount for credit quality, the difference between contractual cash flows and expected cash flows at acquisition is not accreted. Anticipated exit fees, the collection of which is expected, are also recognized over the term of the loan as an adjustment to yield.

Debt and preferred equity investments are placed on a non-accrual status at the earlier of the date at which payments become 90 days past due or when, in the opinion of management, a full recovery of interest income becomes doubtful. Interest income recognition on any non-accrual debt or preferred equity investment is resumed when such non-accrual debt or preferred equity investment becomes contractually current and performance is demonstrated to be resumed. Interest is recorded as income on impaired loans only to the extent cash is received.

We may syndicate a portion of the loans that we originate or sell the loans individually. When a transaction meets the criteria for sale accounting, we derecognize the loan sold and recognize gain or loss based on the difference between the sales price and the carrying value of the loan sold. Any related unamortized deferred origination fees, original issue discounts, loan origination costs, discounts or premiums at the time of sale are recognized as an adjustment to the gain or loss on sale, which is included in investment income on the consolidated statement of operations. Any fees received at the time of sale or syndication are recognized as part of investment income.

Asset management fees are recognized on a straight-line basis over the term of the asset management agreement.

Allowance for Doubtful Accounts

We maintain an allowance for doubtful accounts for estimated losses resulting from the inability of our tenants to make required payments. If the financial condition of a specific tenant were to deteriorate, resulting in an impairment of its ability to make payments, additional allowances may be required.

Reserve for Possible Credit Losses

The expense for possible credit losses in connection with debt and preferred equity investments is the charge to earnings to increase the allowance for possible credit losses to the level that we estimate to be adequate, based on Level 3 data, considering delinquencies, loss experience and collateral quality. Other factors considered include geographic trends, product diversification, the size of the portfolio and current economic conditions. Based upon these factors, we establish a provision for possible credit loss on each individual investment. When it is probable that we will be unable to collect all amounts contractually due, the investment is considered impaired.

Where impairment is indicated on an investment that is held to maturity, a valuation allowance is measured based upon the excess of the recorded investment amount over the fair value of the collateral. Any deficiency between the carrying amount of an asset and the calculated value of the collateral is charged to expense. We continue to assess or adjust our estimates based on circumstances of a loan and the underlying collateral. If additional information reflects increased recovery of our investment, we will adjust our reserves accordingly. There were no loan reserves recorded during the years ended December 31, 2017, 2016, and 2015.

Debt and preferred equity investments held for sale are carried at the lower of cost or fair market value using available market information obtained through consultation with dealers or other originators of such investments as well as discounted cash flow models based on Level 3 data pursuant to ASC 820-10. As circumstances change, management may conclude not to sell an investment designated as held for sale. In such situations, the investment will be reclassified at its net carrying value to debt and preferred equity investments held to maturity. For these reclassified investments, the difference between the current carrying value and the expected cash to be collected at maturity will be accreted into income over the remaining term of the investment.

Rent Expense

Rent expense is recognized on a straight-line basis over the initial term of the lease. The excess of the rent expense recognized over the amounts contractually due pursuant to the underlying lease is included in the deferred lease payable on the consolidated balance sheets.

Underwriting Commissions and Costs

Underwriting commissions and costs incurred in connection with our stock offerings are reflected as a reduction of additional paid-in-capital.

Exchangeable Debt Instruments

The initial proceeds from exchangeable debt that may be settled in cash, including partial cash settlements, are bifurcated between a liability component and an equity component associated with the embedded conversion option. The objective of the accounting guidance is to require the liability and equity components of exchangeable debt to be separately accounted for in a manner such that the interest expense on the exchangeable debt is not recorded at the stated rate of interest but rather at an effective rate that reflects the issuer's conventional debt borrowing rate at the date of issuance. We calculate the liability component of exchangeable debt based on the present value of the contractual cash flows discounted at our comparable market conventional debt borrowing rate at the date of issuance. The difference between the principal amount and the fair value of the liability component is reported as a discount on the exchangeable debt that is accreted as additional interest expense from the issuance date through the contractual maturity date using the effective interest method. A portion of this additional interest expense may be capitalized to the development and redevelopment balances qualifying for interest capitalization each period. The liability component of the exchangeable debt is reported net of discounts on our consolidated balance sheets. We calculate the equity component of exchangeable debt based on the difference between the initial proceeds received from the issuance of the exchangeable debt and the fair value of the liability component at the issuance date. The equity component is included in additional paid-in-capital, net of issuance costs, on our consolidated balance sheets. We allocate issuance costs for exchangeable debt between the liability and the equity components based on their relative values.

Transaction Costs

In January 2017, we adopted ASU No. 2017-01, Business Combinations: Clarifying the Definition of a Business, which changed how we account for transaction costs. Prior to January 2017, transaction costs were expensed as incurred. Starting in January 2017, transaction costs for asset acquisitions are capitalized to the investment basis which is then subject to a purchase price allocation based on relative fair value and transaction costs for business combinations or costs incurred on potential transactions which are not consummated are expensed as incurred.

Income Taxes

SL Green is taxed as a REIT under Section 856(c) of the Code. As a REIT, SL Green generally is not subject to Federal income tax. To maintain its qualification as a REIT, SL Green must distribute at least 90% of its REIT taxable income to its stockholders and meet certain other requirements. If SL Green fails to qualify as a REIT in any taxable year, SL Green will be subject to Federal income tax on its taxable income at regular corporate rates. SL Green may also be subject to certain state, local and franchise taxes. Under certain circumstances, Federal income and excise taxes may be due on its undistributed taxable income.

The Operating Partnership is a partnership and, as a result, all income and losses of the partnership are allocated to the partners for inclusion in their respective income tax returns. The only provision for income taxes included in the consolidated statements of operations relates to the Operating Partnership’s consolidated taxable REIT subsidiaries. The Operating Partnership may also be subject to certain state, local and franchise taxes.

Pursuant to amendments to the Code that became effective January 1, 2001, we have elected, and may elect in the future, to treat certain of our existing or newly created corporate subsidiaries as taxable REIT subsidiaries, or TRSs. In general, TRSs may perform non-customary services for the tenants of the Company, hold assets that we cannot hold directly and generally may engage in any real estate or non-real estate related business. The TRSs generate income, resulting in Federal and state income tax liability for these entities.

During the years ended December 31, 2017, 2016 and 2015, we recorded Federal, state and local tax provisions of $4.3 million, $2.8 million, and $3.1 million, respectively. For the year ended December 31, 2017, the Company paid distributions on its common stock of $3.10 per share which represented $1.24 per share of ordinary income and $1.86 per share of capital gains. For the year ended December 31, 2016, the Company paid distributions on its common stock of $2.88 per share which represented $2.48 per share of ordinary income, and $0.40 per share of capital gains. For the year ended December 31, 2015, the Company paid distributions on its common stock of $2.40 per share which represented $0.00 per share of ordinary income and $2.40 per share of capital gains.

We follow a two-step approach for evaluating uncertain tax positions. Recognition (step one) occurs when an enterprise concludes that a tax position, based solely on its technical merits, is more-likely-than-not to be sustained upon examination. Measurement (step two) determines the amount of benefit that is more-likely-than-not to be realized upon settlement. Derecognition of a tax position that was previously recognized would occur when a company subsequently determines that a tax position no longer meets the more-likely-than-not threshold of being sustained. The use of a valuation allowance as a substitute for derecognition of tax positions is prohibited.

On December 22, 2017, the Tax Cuts and Jobs Act (the ‘‘Tax Act’’) was signed into law and makes substantial changes to the Code. Many of the provisions of the Tax Act will require guidance through the issuance of Treasury regulations in order to assess their effect. The Tax Act did not have a material impact on our financial statements for the year ended December, 31, 2017.

Stock-Based Employee Compensation Plans

We have a stock-based employee compensation plan, described more fully in Note 14, "Share-based Compensation."

The Company's stock options are recorded at fair value at the time of issuance. Fair value of the stock options is determined using the Black-Scholes option pricing model. The Black-Scholes model was developed for use in estimating the fair value of traded options, which have no vesting restrictions and are fully transferable. In addition, option valuation models require the input of highly subjective assumptions including the expected stock price volatility. Because our plan has characteristics significantly different from those of traded options and because changes in the subjective input assumptions can materially affect the fair value estimate, in our opinion, the existing models do not necessarily provide a reliable single measure of the fair value of the employee stock options.

Compensation cost for stock options, if any, is recognized over the vesting period of the award. Our policy is to grant options with an exercise price equal to the quoted closing market price of the Company's common stock on either the grant date or the date immediately preceding the grant date. Awards of stock or restricted stock are expensed as compensation over the benefit period based on the fair value of the stock on the grant date.

For share-based awards with a performance or market measure, we recognize compensation cost over the requisite service period, using the accelerated attribution expense method. The requisite service period begins on the date the compensation committee of our board of directors authorizes the award, adopts any relevant performance measures and communicates the award to the employees. For programs with awards that vest based on the achievement of a performance condition or market condition, we determine whether it is probable that the performance condition will be met, and estimate compensation cost based on the fair value of the award at the applicable award date estimated using a binomial model or market quotes. For share-based awards for which there is no pre-established performance measure, we recognize compensation cost over the service vesting period, which represents the requisite service period, on a straight-line basis. In accordance with the provisions of our share-based incentive compensation plans, we accept the return of shares of the Company's common stock, at the current quoted market price, from certain key employees to satisfy minimum statutory tax-withholding requirements related to shares that vested during the period.

Awards can also be made in the form of a separate series of units of limited partnership interest in the Operating Partnership called long-term incentive plan units, or LTIP units. LTIP units, which can be granted either as free-standing awards or in tandem with other awards under our stock incentive plan, are valued by reference to the value of the Company's common stock at the time of grant, and are subject to such conditions and restrictions as the compensation committee of the Company's board of directors may determine, including continued employment or service, computation of financial metrics and/or achievement of pre-established performance goals and objectives.

Derivative Instruments

In the normal course of business, we use a variety of commonly used derivative instruments, such as interest rate swaps, caps, collars and floors, to manage, or hedge, interest rate risk. Effectiveness is essential for those derivatives that we intend to qualify for hedge accounting. Some derivative instruments are associated with an anticipated transaction. In those cases, hedge effectiveness criteria also require that it be probable that the underlying transaction occurs. Instruments that meet these hedging criteria are formally designated as hedges at the inception of the derivative contract.

To determine the fair values of derivative instruments, we use a variety of methods and assumptions that are based on market conditions and risks existing at each balance sheet date. For the majority of financial instruments including most derivatives, long-term investments and long-term debt, standard market conventions and techniques such as discounted cash flow analysis, option pricing models, replacement cost, and termination cost are used to determine fair value. All methods of assessing fair value result in a general approximation of value, and such value may never actually be realized.

In the normal course of business, we are exposed to the effect of interest rate changes and limit these risks by following established risk management policies and procedures including the use of derivatives. To address exposure to interest rates, derivatives are used primarily to fix the rate on debt based on floating-rate indices and manage the cost of borrowing obligations.

We use a variety of conventional derivative products. These derivatives typically include interest rate swaps, caps, collars and floors. We expressly prohibit the use of unconventional derivative instruments and using derivative instruments for trading or speculative purposes. Further, we have a policy of only entering into contracts with major financial institutions based upon their credit ratings and other factors.

We may employ swaps, forwards or purchased options to hedge qualifying forecasted transactions. Gains and losses related to these transactions are deferred and recognized in net income as interest expense in the same period or periods that the underlying transaction occurs, expires or is otherwise terminated.

Hedges that are reported at fair value and presented on the balance sheet could be characterized as cash flow hedges or fair value hedges. Interest rate caps and collars are examples of cash flow hedges. Cash flow hedges address the risk associated with future cash flows of interest payments. For all hedges held by us and which were deemed to be fully effective in meeting the hedging objectives established by our corporate policy governing interest rate risk management, no net gains or losses were reported in earnings. The changes in fair value of hedge instruments are reflected in accumulated other comprehensive income. For derivative instruments not designated as hedging instruments, the gain or loss, resulting from the change in the estimated fair value of the derivative instruments, is recognized in current earnings during the period of change.

Earnings per Share of the Company

The Company presents both basic and diluted earnings per share, or EPS. Basic EPS excludes dilution and is computed by dividing net income or loss attributable to common stockholders by the weighted average number of common shares outstanding during the period. Basic EPS includes participating securities, consisting of unvested restricted stock that receive nonforfeitable dividends similar to shares of common stock. Diluted EPS reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock, where such exercise or conversion would result in a lower EPS amount. Diluted EPS also includes units of limited partnership interest. The dilutive effect of stock options is reflected in the weighted average diluted outstanding shares calculation by application of the treasury stock method. There is no dilutive effect for the exchangeable senior notes as the conversion premium will be paid in cash.

Earnings per Unit of the Operating Partnership

The Operating Partnership presents both basic and diluted earnings per unit, or EPU. Basic EPU excludes dilution and is computed by dividing net income or loss attributable to common unitholders by the weighted average number of common units outstanding during the period. Basic EPU includes participating securities, consisting of unvested restricted units that receive nonforfeitable dividends similar to shares of common units. Diluted EPU reflects the potential dilution that could occur if securities or other contracts to issue common units were exercised or converted into common units, where such exercise or conversion would result in a lower EPU amount. The dilutive effect of unit options is reflected in the weighted average diluted outstanding units calculation by application of the treasury stock method. There is no dilutive effect for the exchangeable senior notes as the conversion premium will be paid in cash.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.

Concentrations of Credit Risk

Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash investments, debt and preferred equity investments and accounts receivable. We place our cash investments with high quality financial institutions. The collateral securing our debt and preferred equity investments is located in the New York metropolitan area. See Note 5, "Debt and Preferred Equity Investments."

We perform ongoing credit evaluations of our tenants and require most tenants to provide security deposits or letters of credit. Though these security deposits and letters of credit are insufficient to meet the total value of a tenant's lease obligation, they are a measure of good faith and a source of funds to offset the economic costs associated with lost revenue and the costs associated with re-tenanting a space. The properties in our real estate portfolio are located in the New York metropolitan area. The tenants located in our buildings operate in various industries. Other than one tenant, Credit Suisse Securities (USA), Inc., who accounts for 8.0% of our share of annualized cash rent, no other tenant in our portfolio accounted for more than 5.0% of our share of annualized cash rent, including our share of joint venture annualized rent, at December 31, 2017. For the year ended December 31, 2017, 7.1%, 7.1%, 7.0%, 6.0%, and 5.6% of our annualized cash rent for consolidated properties was attributable to 11 Madison Avenue, 1185 Avenue of the Americas, 1515 Broadway, 420 Lexington Avenue, and One Madison Avenue, respectively. Annualized cash rent for all other consolidated properties was below 5.0%.

For the year ended December 31, 2016, 8.8%, 6.9%, 6.1%, 5.9%, and 5.6% of our annualized cash rent for consolidated properties was attributable to 1515 Broadway, 1185 Avenue of the Americas, 11 Madison Avenue, 420 Lexington Avenue, and One Madison Avenue, respectively. For the year ended December 31, 2015, 8.9%, 8.2%, 6.6%, 6.5%, and 5.6% of our annualized cash rent for consolidated properties was attributable to 1515 Broadway, 388-390 Greenwich Street, 1185 Avenue of the Americas, 11 Madison Avenue, and 420 Lexington Avenue, respectively.

As of December 31, 2017, 68.4% of our work force is covered by six collective bargaining agreements and 55.0% of our work force, which services substantially all of our properties, is covered by a collective bargaining agreement, which expires in December 2019. Approximately 8.8% of our work force is covered by a collective bargaining agreement which expires in December 2018. See Note 19, "Benefits Plans."

Reclassification

Certain prior year balances have been reclassified to conform to our current year presentation.

Accounting Standards Updates

In August 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-12, Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities. The amendments in the new standard will permit more flexibility in hedging interest rate risk for both variable rate and fixed rate financial instruments. The standard will also enhance the presentation of hedge results in the financial statements. The guidance is effective for fiscal years beginning after December 15, 2018 and early adoption is permitted. The Company has not yet adopted the guidance, and does not expect a material impact on the Company’s consolidated financial statements when the new standard is implemented.

In May 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-09, Compensation - Stock Compensation (Topic 718), Scope of Modification Accounting. The guidance clarifies the changes to the terms or conditions of a share-based payment award that require an entity to apply modification accounting in Topic 718. The guidance is effective for fiscal years beginning after December 15, 2017 and early adoption is permitted. The Company has not yet adopted the guidance, and does not expect a material impact on the Company’s consolidated financial statements when the new standard is implemented.

In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The guidance clarifies the definition of a business and provides guidance to assist with determining whether transactions should be accounted for as acquisitions of assets or businesses. The main provision is that an acquiree is not a business if substantially all of the fair value of the gross assets is concentrated in a single identifiable asset or group of assets. The Company adopted the guidance on the issuance date effective January 5, 2017. The Company expects that most of its real estate acquisitions will be considered asset acquisitions under the new guidance and that transaction costs will be capitalized to the investment basis which is then subject to a purchase price allocation based on relative fair value.

In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The guidance will require entities to show the changes on the total cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between these items on the statement of cash flows. The guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The ASU provides final guidance on eight cash flow issues, including debt prepayment or debt extinguishment costs, contingent consideration payments made after a business combination, distributions received from equity method investees, separately identifiable cash flows and application of the predominance principle, and others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company adopted the guidance effective January 1, 2017 and there was no impact on the Company’s consolidated financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The guidance changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance replaces the current ‘incurred loss’ model with an ‘expected loss’ approach. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted after December 2018. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements.

In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The guidance simplifies the accounting for share-based payment award transactions including: income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The guidance is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company adopted the guidance effective January 1, 2017 and there was no material impact on the Company’s consolidated financial statements.

In March 2016, the FASB issued ASU 2016-07, Investments Equity Method and Joint Ventures (Topic 323). The guidance eliminates the requirement that an entity retroactively adopt the equity method of accounting if an investment qualifies for use of the equity method as a result of an increase in the level of ownership or degree of influence. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor’s previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. The Company adopted the guidance effective January 1, 2017 and there was no impact on the Company’s consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, Leases. The guidance requires lessees to recognize lease assets and lease liabilities for those leases classified as operating leases under the previous standard. Depending on the lease classification, lessees will recognize expense based on the effective interest method for finance leases or on a straight-line basis for operating leases. The accounting applied by a lessor is largely unchanged from that applied under the previous standard. One of the potential impacts on the Company may be the presentation and disclosure in the financial statements of non-lease components such as charges to tenants for a building’s operating expenses. As currently written, the guidance would require that the non-lease components be presented separately from the lease components in both the Consolidated Statements of Operations and Consolidated Balance Sheets. In January 2018, the FASB issued an exposure draft, Leases (Topic 842) Targeted Improvements, which would provide lessors with a practical expedient to not separate non-lease components from the related lease component under certain conditions. We anticipate the majority of our leases would qualify for the practical expedient. We expect this guidance to be finalized in 2018 and, as a result, we would adopt the practical expedient. Another impact is the measurement and presentation of ground leases under which the Company is lessee. The Company is required to record a liability for the obligation to make payments under the lease and an asset for the right to use the underlying asset during the lease term and will also apply the new expense recognition requirements given the lease classification. The Company is currently quantifying these impacts. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company expects to adopt this guidance January 1, 2019 and will apply the modified retrospective approach.

In January 2016, the FASB issued ASU 2016-01 (Subtopic 825-10), Recognition and Measurement of Financial Assets and Financial Liabilities. The guidance requires entities to measure equity investments that do not result in consolidation and are not accounted for under the equity method at fair value through earnings to record changes in instruments-specific credit risk for financial liabilities measured under the fair value option in other comprehensive income, use the exit price notion when measuring an instrument’s fair value for disclosure and to separately present financial assets and liabilities by measurement category and form of instrument on the balance sheet or in the notes to the financial statements. The guidance is effective for fiscal years beginning after December 15, 2017, and for interim periods therein. The Company has not yet adopted this new guidance and does not expect a material impact on the Company’s consolidated financial statements when the new standard is implemented.

In May 2014, the FASB issued a new comprehensive revenue recognition guidance which requires us to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods and services (ASU 2014-09). The FASB also issued implementation guidance in March 2016, April 2016 and May 2016 - ASU’s 2016-08, 2016-10 and 2016-12, respectively. These ASUs are effective for annual and interim periods beginning after December 15, 2017. The Company will adopt this guidance January 1, 2018. Since the Company’s revenue is related to leasing activities, the adoption of this guidance will not have a material impact on the consolidated financial statements. The new guidance is applicable to service contracts with joint ventures for which the Company earns property management fees, leasing commissions and development and construction fees. The adoption of this new guidance does not change the accounting for these fees as the pattern of recognition of revenue does not change with the new guidance. We will continue to recognize revenue over time on these contracts because the customer simultaneously receives and consumes the benefits provided by our performance. Thus, the analysis of our contracts under the new revenue recognition standard is consistent with our current revenue recognition model.

In February 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-05 to clarify the scope of asset derecognition guidance in Subtopic 610-20, which also provided guidance on accounting for partial sales of nonfinancial assets. Subtopic 610-20 was issued in May 2014 as part of ASU 2014-09. The Company will adopt this guidance January 1, 2018, and apply the modified retrospective approach. Additionally, the Company will elect to adopt the practical expedient under ASC 606, Revenue from Contracts with Customers, which allows an entity to apply the guidance to only to contracts with non-customers that are open based on the ASU 360-20, Real Estate Sales, (i.e. failed sales) as of the adoption date. The Company had one open contract in 2017 with a non-customer that will be evaluated under ASC 610-20. The Company entered into an agreement to sell a portion of their interest in an entity that held a controlling interest in the property at 1515 Broadway. Upon execution of the agreement in 2017, the transaction was evaluated under ASC 360-20, Real Estate Sales, and did not meet the criteria for sale accounting. Upon adoption of ASC 606, this contract will have met the criteria for sale accounting under ASC 610-20 and will be recorded in the first quarter of 2018 as an adjustment to beginning retained earnings. Through the sale, the Company no longer retains a controlling interest, as defined in ASC 810, Consolidation, and the impact of this adjustment will be a gain of $0.6 billion from the sale of the partial interest and related step-up in basis to fair value of the non-controlling interest retained. The Company will use the purchase price paid by the third party as an indicator of fair value. This purchase price will be allocated to the assets and liabilities, including identified intangibles. Under this methodology the leases are ascribed an in-place lease intangible value as well as an above or below market lease intangible value which will be amortized over the remaining term of the associated leases.