Basis of Presentation and Significant Accounting Policies

Basis of Presentation

The consolidated financial statements of the Company include the consolidated financial position and results of operations of the Company, the Operating Partnership, the Finance Partnership, KSLLC, and all of our wholly-owned subsidiaries. The consolidated financial statements of the Operating Partnership include the consolidated financial position and results of operations of the Operating Partnership, the Finance Partnership, KSLLC, and all wholly-owned and controlled subsidiaries of the Operating Partnership. All intercompany balances and transactions have been eliminated in the consolidated financial statements.

Consolidated Variable Interest Entities

As of December 31, 2012 the consolidated financial statements of the Company and the Operating Partnership also included two variable interest entities ("VIEs") in which we are deemed to be the primary beneficiary. During the year ended December 31, 2012, one operating property and one development project were acquired in two separate transactions and transferred to two special purpose VIEs to facilitate potential Section 1031 Exchanges. To realize the tax deferral available under the Section 1031 Exchange, the Company must complete the Section 1031 Exchanges, if any, and take title to the to-be-exchanged properties within 180 days of the acquisition dates (see Note 3). The VIEs were terminated subsequent to year-end. The impact of consolidating the VIEs increased the Company's total assets and liabilities by approximately $337.0 million (of which $319.8 million is related to real estate held for investment on our consolidated balance sheets) and $111.1 million, respectively, at December 31, 2012. As of December 31, 2011, the consolidated financial statements of the Company and the Operating Partnership included one VIE in which we were deemed to be the primary beneficiary, which was established in September 2011 to facilitate a Section 1031 Exchange. The impact of consolidating this VIE increased the Company's total assets and liabilities by approximately $108.5 million (of which $101.4 million was related to real estate held for investment on our consolidated balance sheets) and $7.3 million, respectively, at December 31, 2011. This Section 1031 Exchange was completed in January 2012 and this entity was no longer a VIE at December 31, 2012.

Change in Segment Reporting

At December 31, 2012 we only had one segment, which was our office properties segment, because all of our industrial properties were sold during the year ended December 31, 2012. During the year ended December 31, 2011 we had one reportable segment, which was our office properties segment, and we had one non-reportable segment, which was our industrial properties segment.

For the year ended December 31, 2011, the amount of revenues and Net Operating Income generated by our industrial properties, in relation to our total consolidated operating portfolio revenues and Net Operating Income, fell below the required 10% quantitative reporting threshold and the industrial properties were no longer considered to be a reportable segment under GAAP. For the year ended December 31, 2010, the amount of revenues and Net Operating Income generated by our industrial properties, in relation to our total consolidated operating portfolio revenues and Net Operating Income, was greater than the required 10% quantitative reporting threshold and the industrial properties were considered to be a reportable segment under GAAP.

Significant Accounting Policies

Acquisitions

We record the acquired tangible and intangible assets and assumed liabilities of acquisitions of operating properties and development and redevelopment opportunities that meet the accounting criteria to be accounted for as business combinations at fair value at the acquisition date. The acquired assets and assumed liabilities for an acquisition generally include but are not limited to: land, buildings and improvements, undeveloped land and construction in progress; and identified tangible and intangible assets and liabilities associated with in-place leases, including tenant improvements, leasing costs, value of above-market and below-market operating leases and ground leases, acquired in-place lease values and tenant relationships, if any. Any debt assumed and equity (including common units of the Operating Partnership) issued in connection with a property acquisition is recorded at fair value on the date of acquisition.

The fair value of land is derived from comparable sales of land within the same submarket and/or region. The fair value of buildings and improvements, tenant improvements, and leasing costs are based upon current market replacement costs and other relevant market rate information.

The fair value of the above-market or below-market component of an acquired in-place operating lease is based upon the present value (calculated using a market discount rate) of the difference between (i) the contractual rents to be paid pursuant to the lease over its remaining non-cancellable lease term and (ii) management's estimate of the rents that would be paid using fair market rental rates and rent escalations at the date of acquisition measured over the remaining non-cancellable term of the lease for above-market operating leases and the initial non-cancellable term plus the term of any below-market fixed rate renewal options, if applicable, for below-market operating leases. Our below-market operating leases generally do not include fixed rate or below-market renewal options. The amounts recorded for above-market operating leases are included in deferred leasing costs and acquisition-related intangibles, net on the balance sheet and are amortized on a straight-line basis as a reduction of rental income over the remaining term of the applicable leases. The amounts recorded for below-market operating leases are included in deferred revenue and acquisition-related liabilities, net on the balance sheet and are amortized on a straight-line basis as an increase to rental income over the remaining term of the applicable leases plus the term of any below-market fixed rate renewal options, if applicable.

The fair value of acquired in-place leases is derived based on management's assessment of lost revenue and costs incurred for the period required to lease the "assumed vacant" property to the occupancy level when purchased. The amount recorded for acquired in-place leases is included in deferred leasing costs and acquisition-related intangibles, net on the balance sheet and amortized as an increase to depreciation and amortization expense over the remaining term of the applicable leases.

We record the acquisition of undeveloped land that does not meet the accounting criteria to be accounted for as business combinations and the subsequent acquisition of the fee interest in land underlying our properties at the purchase price paid and capitalize the associated acquisition costs. During the year ended December 31, 2012, we capitalized $0.7 million in acquisition costs associated with the acquisition of undeveloped land.

Fully amortized intangible assets are written off on January 1st of each fiscal year.

Operating Properties

Operating properties are generally carried at historical cost less accumulated depreciation. Properties held for sale are reported at the lower of the carrying value or the fair value less estimated cost to sell. The cost of operating properties includes the purchase price or development costs of the properties. Costs incurred for the renovation and betterment of the operating properties are capitalized to our investment in that property. Maintenance and repairs are charged to expense as incurred.

When evaluating properties to be held and used for potential impairment, we first evaluate whether there are any indicators of impairment for any of our properties. If any impairment indicators are present for a specific property, we then perform an undiscounted cash flow analysis and compare the net carrying amount of the property to the property's estimated undiscounted future cash flow over the anticipated holding period. If the estimated undiscounted future cash flow is less than the net carrying amount of the property, we then perform an impairment loss calculation to determine if the fair value of the property is less than the net carrying value of the property. Our impairment loss calculation compares the net carrying amount of the property to the property's estimated fair value, which may be based on estimated discounted future cash flow calculations or third-party valuations or appraisals. We would recognize an impairment loss if the asset's net carrying amount exceeds the asset's estimated fair value. If we were to recognize an impairment loss, the estimated fair value of the asset (less costs to sell for assets held for sale) would become its new cost basis. For a depreciable long-lived asset, the new cost basis would be depreciated (amortized) over the remaining useful life of that asset. We did not record any impairment losses for the periods presented.

Cost Capitalization

All costs clearly associated with the development, redevelopment and construction of a property are capitalized as project costs, including internal compensation costs. In addition, the following costs are capitalized as project costs during periods in which activities necessary to prepare development and redevelopment properties for its intended use are in progress: pre-construction costs essential to the development of the property, interest, real estate taxes, insurance.


•	For development and redevelopment properties that are pre-leased, we cease capitalization when revenue recognition commences, which is upon substantial completion of tenant improvements.

•

For development and redevelopment properties that are not pre-leased, we may not immediately build out the tenant improvements. Therefore we cease capitalization when revenue recognition commences upon substantial completion of the tenant improvements, but in any event not later than one year after the cessation of major construction activities. We also cease capitalization on a development or redevelopment property when activities necessary to prepare the property for its intended use have been suspended.


•	For development or redevelopment properties with multiple tenants and staged leasing, we cease capitalization and begin depreciation on the portion of the development or redevelopment property for which revenue recognition has commenced.

Once major construction activity has ceased and the development or redevelopment property is in the lease-up phase, the costs capitalized to construction in progress are transferred to land and improvements, buildings and improvements, and deferred leasing costs on our consolidated balance sheets as the historical cost of the property.

Depreciation and Amortization of Buildings and Improvements

The cost of buildings and improvements and tenant improvements are depreciated using the straight-line method of accounting over the estimated useful lives set forth in the table below. Depreciation expense for buildings and improvements, including discontinued operations, for the three years ended December 31, 2012, 2011, and 2010 was $125.9 million, $106.0 million and $86.3 million, respectively.



Asset Description	Depreciable Lives
Buildings and improvements	25 – 40 years
Tenant improvements	1 – 20 years⁽¹⁾

________________________


(1)	Tenant improvements are amortized over the shorter of the lease term or the estimated useful life.

Discontinued Operations and Properties Held for Sale

The revenues and expenses of operating properties that have been sold, if material, and the revenues and expenses of operating properties that have been classified as held for sale, if material, are reported in the consolidated statements of operations as discontinued operations for all periods presented through the date of the applicable disposition. The net gains (losses) on disposition of operating properties are reported in the consolidated statements of operations as discontinued operations in the period the properties are sold. In determining whether the revenues, expenses, and net gains (losses) on dispositions of operating properties are reported as discontinued operations, we evaluate whether we have any significant continuing involvement in the operations, leasing, or management of the sold property. If we were to determine that we had any significant continuing involvement, the revenues, expenses and net gain (loss) on dispositions of the operating property would not be recorded in discontinued operations.

An operating property is classified as held for sale when certain criteria are met, including but not limited to the availability of the asset for immediate sale, the existence of an active program to locate a buyer, and the probable sale or transfer of the asset within one year. If such criteria are met, we present the applicable assets and liabilities related to the property held for sale, if material, separately on the balance sheet and we would cease to record depreciation and amortization expense. Properties held for sale are reported at the lower of their carrying value or their estimated fair value less the estimated costs to sell. As of December 31, 2012, we did not have any buildings classified as held for sale, and as of December 31, 2011, we had two buildings classified as held for sale, which were sold in January 2012 (see Note 17).

Revenue Recognition

We recognize revenue from rent, tenant reimbursements, parking, and other revenue once all of the following criteria are met:


•	the agreement has been fully executed and delivered;


•	services have been rendered;


•	the amount is fixed or determinable; and


•	the collectability of the amount is reasonably assured.

Minimum annual rental revenues are recognized in rental revenues on a straight-line basis over the term of the related 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, management records the cost to construct the tenant improvements as a capital asset. In addition, management records the cost of certain tenant improvements paid for or reimbursed by tenants as capital assets when management concludes that we are the owner of such tenant improvements. For these tenant improvements, management records the amount funded or reimbursed by tenants as deferred revenue, which is amortized on a straight-line basis as additional rental income over the term of the related lease.

When management concludes that the tenant is the owner of tenant improvements for accounting purposes, management records our contribution towards those improvements as a lease incentive, which is included in deferred leasing costs and acquisition-related intangibles, net on our consolidated balance sheets and amortized as a reduction to rental income on a straight-line basis over the term of the lease.

Tenant Reimbursements

Reimbursements from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes, and other recoverable costs, are recognized as revenue in the period the recoverable costs are incurred. Tenant reimbursements are recognized and recorded on a gross basis, as we are generally the primary obligor with respect to purchasing goods and services from third-party suppliers, have discretion in selecting the supplier, and have credit risk.

Other Property Income

Other property income primarily includes amounts recorded in connection with lease terminations and tenant bankruptcy settlement payments. Lease termination fees are amortized over the remaining lease term, if applicable. If there is no remaining lease term, they are recognized when received and realized. Other property income also includes miscellaneous income from tenants, such as fees related to the restoration of leased premises to their original condition and fees for late rental payments.

Allowances for Uncollectible Tenant and Deferred Rent Receivables

We carry our current and deferred rent receivables net of allowances for uncollectible amounts. Our determination of the adequacy of these allowances is based primarily upon evaluations of individual receivables, current economic conditions, historical loss experience, and other relevant factors. The allowances are increased or decreased through the provision for bad debts on our consolidated statements of operations.

Cash and Cash Equivalents

We consider all highly-liquid investments with original maturities of three months or less to be cash equivalents.

Restricted Cash

Restricted cash consists of cash proceeds from dispositions that are temporarily held at qualified intermediaries for purposes of facilitating potential Section 1031 Exchanges and cash held in escrow related to acquisition holdbacks. Restricted cash also includes cash held as collateral to provide credit enhancement for the Operating Partnership's mortgage debt, including cash reserves for capital expenditures, tenant improvements, and property taxes.

Marketable Securities / Deferred Compensation Plan

Marketable securities reported in our consolidated balance sheets represent the assets held in connection with the Kilroy Realty Corporation 2007 Deferred Compensation Plan (the "Deferred Compensation Plan") (see Note 13). The Deferred Compensation Plan assets are held in a limited rabbi trust and invested in various mutual and money market funds. As a result, the marketable securities are treated as trading securities for financial reporting purposes and are adjusted to fair value at the end of each accounting period, with the corresponding gains and losses recorded in interest income and other net investment gains.

At the time eligible management employees ("Participants") defer compensation or earn mandatory Company contributions, or if we were to make a discretionary contribution, we record compensation cost and a corresponding deferred compensation plan liability, which is included in accounts payable, accrued expenses, and other liabilities on our consolidated balance sheets. This liability is adjusted to fair value at the end of each accounting period based on the performance of the benchmark funds selected by each Participant, and the impact of adjusting the liability to fair value is recorded as an increase or decrease to compensation cost. The impact of adjusting the deferred compensation plan liability to fair value and the changes in the value of the marketable securities held in connection with the Deferred Compensation Plan generally offset and therefore does not significantly impact net income.

Deferred Leasing Costs

Costs incurred in connection with successful property leasing are capitalized as deferred leasing costs and classified as investment activities in the statement of cash flows. Deferred leasing costs consist primarily of leasing commissions and also include certain internal payroll costs and lease incentives, which are amortized using the straight-line method of accounting over the lives of the leases which generally range from one to 20 years. We reevaluate the remaining useful lives of leasing costs as the creditworthiness of our tenants and economic and market conditions change. If we determine that the estimated remaining life of a lease has changed, we adjust the amortization period accordingly. Fully amortized deferred leasing costs are written off on January 1st of each fiscal year.

Deferred Financing Costs

Financing costs related to the origination or assumption of long-term debt are deferred and generally amortized using the straight-line method of accounting, which approximates the effective interest method, over the contractual terms of the applicable financings. As of December 31, 2012 and 2011, deferred financing costs were reported net of accumulated amortization of $16.6 million and $16.8 million, respectively.

Debt Discounts and Premiums

Original issuance debt discounts and discounts/premiums related to recording debt acquired in connection with operating property acquisitions at fair value are generally amortized and accreted on a straight-line basis, which approximates the effective interest method. Discounts are recorded as additional interest expense from date of issuance or acquisition through the contractual maturity date of the related debt. Premiums are recorded as a reduction to interest expense from the date of issuance or acquisition through the contractual maturity date of the related debt. Our secured debt is presented including unamortized premiums of $7.2 million and $0.8 million as of December 31, 2012 and 2011, respectively. Our unsecured senior notes are presented net of unamortized discounts of $2.1 million and $2.4 million, as of December 31, 2012 and 2011, respectively.

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 liability and equity components of exchangeable debt are 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 a 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 is 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.

Gains and Losses on Early Extinguishment of Debt

Gains and losses on early extinguishment of debt represents the gains and losses recorded in connection with the repurchases of portions of our 3.25% Exchangeable Notes, which were outstanding during the year ended December 31, 2011 and repaid during the year ended December 31, 2012 (see Note 7). We calculate the gain or loss on early extinguishment of debt as the difference on the repurchase date between the estimated fair value of the liability component and the net carrying amount of the repurchased exchangeable debt. Deferred financing costs are written off against the gain on early extinguishment of debt or added to the loss on early extinguishment of debt in proportion to the exchangeable debt repurchased.

Noncontrolling Interests in the Company's Consolidated Financial Statements

Noncontrolling interests in the Company's consolidated financial statements represent the issued 1,510,000 7.45% Series A Cumulative Redeemable Preferred Units of the Operating Partnership (“Series A Preferred Units”) which were outstanding at December 31, 2011 and common limited partnership interests in the Operating Partnership not held by the Company (“noncontrolling common units”).

The Series A Preferred Units were presented in the temporary equity section of the Company's consolidated balance sheets after total liabilities and before equity and reported at redemption value, less issuance costs, given that the Series A Preferred Units contained a right of redemption at the option of the holders in the event of certain corporate events. On August 15, 2012, the Operating Partnership redeemed all Series A Preferred Units (see Note 9).

Noncontrolling common units are presented in the equity section of the Company's consolidated balance sheets and reported at their proportionate share of the net assets of the Operating Partnership. Noncontrolling interests with redemption provisions that permit the issuer to settle in either cash or shares of common stock at the option of the issuer must be further evaluated to determine whether equity or temporary equity classification on the balance sheet is appropriate. Since the common units contain such a provision, we evaluated the accounting guidance and determined that the common units qualify for equity presentation in the Company's consolidated financial statements (see Note 9).

Net income attributable to noncontrolling common units is allocated based on their relative ownership percentage of the Operating Partnership during the reported period. The noncontrolling interest ownership percentage is determined by dividing the number of noncontrolling common units by the total number of common units outstanding. The issuance or redemption of additional shares of common stock or common units results in changes to the noncontrolling interest percentage as well as the total net assets of the Company. As a result, all equity transactions result in an allocation between equity and the noncontrolling interest in the Company’s consolidated balance sheets and statements of equity to account for the changes in the noncontrolling interest ownership percentage as well as the change in total net assets of the Company.

Preferred Partnership Interests on the Operating Partnership's Consolidated Balance Sheets

Preferred partnership interests of the Operating Partnership represent the issued and outstanding 4,000,000 6.875% Series G Cumulative Redeemable Preferred Units ("Series G Preferred Units") and the 4,000,000 6.375% Series H Cumulative Redeemable Preferred Units ("Series H Preferred Units"), which were outstanding as of December 31, 2012. The Series A Preferred Units, 1,610,000 7.80% Series E Cumulative Redeemable Preferred Units ("Series E Preferred Units") and 3,450,000 7.50% Series F Cumulative Redeemable Preferred Units ("Series F Preferred Units") were outstanding as of December 31, 2011 and redeemed during the year ended December 31, 2012.

The Series A Preferred Units were presented in the temporary equity section of the Operating Partnership's consolidated balance sheets after total liabilities and before equity and reported at redemption value, less issuance costs, given that the Series A Preferred Units contain a right of redemption at the option of the holders in the event of certain corporate events (see Note 9).

The Series G and Series H Preferred Units are presented in the permanent equity section of the Operating Partnership's consolidated balance sheets given that the Series G and Series H Preferred Units may be redeemed only at our option (see Note 11). The Company is the holder of both the Series G and Series H Preferred Units and for each Series G and Series H Preferred Unit, the Company has an equivalent number of shares of the Company's 6.875% Series G Cumulative Redeemable Preferred Stock and shares of the Company's 6.375% Series H Cumulative Redeemable Preferred Stock publicly issued and outstanding. The Series E Preferred Units and Series F Preferred Units were presented in the permanent equity section of the Operating Partnership's consolidated balance sheets at December 31, 2011, similar to the Series G and Series H Preferred Units.

Common Partnership Interests on the Operating Partnership's Consolidated Balance Sheets

The common units held by the Company and the noncontrolling common units held by the common limited partners are both presented in the permanent equity section of the Operating Partnership's consolidated balance sheets in partners' capital. The redemption rights of the noncontrolling common units permit us to settle the redemption obligation in either cash or shares of the Company's common stock at our option (see Note 9).

Noncontrolling Interests on the Operating Partnership's Consolidated Balance Sheets

Noncontrolling interests of the Operating Partnership represent the Company's 1.0% general partnership interest in the Finance Partnership. This noncontrolling interest is presented in the permanent equity section of the Operating Partnership's consolidated balance sheets given that these interests are not convertible or redeemable into any other ownership interest of the Company or the Operating Partnership.

Equity Offerings

Underwriting commissions and offering costs incurred in connection with common equity offerings and our at-the-market stock offering program (see Note 10) are reflected as a reduction of additional paid-in capital. Issuance costs incurred in connection with preferred equity offerings are reflected as a reduction of the carrying value of the preferred equity.

The Company records preferred stock issuance costs as a non-cash preferred equity distribution at the time we notify the holders of preferred stock or units of our intent to redeem such shares or units.

The net proceeds from any equity offering of the Company are contributed to the Operating Partnership in exchange for a number of common or preferred units equivalent to the number of shares of common or preferred stock issued and are reflected in the Operating Partnership's consolidated financial statements as an increase in partners' capital.

Share-based Incentive Compensation Accounting

Compensation cost for all share-based awards, including options, requires measurement at estimated fair value on the grant date and recognition of the compensation cost is recognized over the service vesting period, which represents the requisite service period, on a straight-line basis. The grant date fair value of market measure-based share-based compensation plans are calculated using a Monte Carlo simulation pricing model. The grant date fair value of stock option grants is calculated using the Black-Scholes valuation model.

For share-based awards in which the performance period precedes the grant date, we recognize compensation cost over the requisite service period, which includes both the performance and service vesting periods, using the accelerated attribution expense method. The requisite service period begins on the date the Executive Compensation Committee authorizes the award and adopts any relevant performance measures.

During the performance period for a share-based award program when the performance period precedes the grant date, we estimate the total compensation cost of the potential future awards. We then record compensation cost equal to the portion of the requisite service period that has elapsed through the end of the reporting period. For programs with performance-based measures, the total estimated compensation cost is based on our most recent estimate of the probable achievement of the pre-established specific corporate performance measures. These estimates are based on our latest internal forecasts for each performance measure. For programs with market measures, the total estimated compensation cost is based on the fair value of the award at the reporting date.

In accordance with the provisions of our share-based incentive compensation plans, we accept the return of shares of Company 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.

For share based awards granted by the Company, the Operating Partnership issues a number of common units equal to the number of shares of common stock ultimately granted by the Company in respect of such awards.

Basic and Diluted Net Income (Loss) Available to Common Stockholders per Share

Basic net income (loss) available to common stockholders per share is computed by dividing net income (loss) available to common stockholders, after the allocation of income to participating securities, by the weighted-average number of vested shares of common stock outstanding, for the period. Diluted net income (loss) available to common stockholders per share is computed by dividing net income (loss) available for common stockholders, after the allocation of income to participating securities, by the sum of the weighted-average number of shares of common stock outstanding for the period plus the assumed exercise of all dilutive securities. The impact of the outstanding common units is considered in the calculation of diluted net income (loss) available to common stockholders per share. The common units are not reflected in the diluted net income (loss) available to common stockholders per share calculation because the exchange of common units into common stock is on a one for one basis, and the common units are allocated net income on a per share basis equal to the common stock (see Note 19). Accordingly, any exchange would not have any effect on diluted net income (loss) available to common stockholders per share.

Nonvested share-based payment awards (including nonvested restricted stock units ("RSUs") and dividend equivalents issued to holders of RSUs) containing nonforfeitable rights to dividends or dividend equivalents are accounted for as participating securities and included in the computation of basic and diluted net income (loss) available to common stockholders per share pursuant to the two-class method. The dilutive effect of stock options are reflected in the weighted average diluted outstanding shares calculation by application of the treasury stock method. The dilutive effect of Exchangeable Notes are reflected in the weighted average diluted outstanding shares calculation when the average quoted trading price of the Company's common stock on the NYSE for the periods presented was above the Exchangeable Notes exchange prices. The dilutive effect of the outstanding nonvested shares of common stock (“nonvested shares”) and RSUs that have not yet been granted but are contingently issuable under the share-based compensation programs is reflected in the weighted average diluted shares calculation by application of the treasury stock method at the beginning of the quarterly period in which all necessary conditions have been satisfied.

Basic and Diluted Net Income (Loss) Available to Common Unitholders per Unit

Basic net income (loss) available to common unitholders per unit is computed by dividing net income (loss) available to common unitholders, after the allocation of income to participating securities, by the weighted-average number of vested common units outstanding, for the period. Diluted net income (loss) available to common unitholders per unit is computed by dividing net income (loss) available to common unitholders, after the allocation of income to participating securities, by the sum of the weighted-average number of common units outstanding for the period plus the assumed exercise of all dilutive securities.

The dilutive effect of stock options, Exchangeable Notes, outstanding nonvested shares, RSUs, and awards containing nonforfeitable rights to dividend equivalents are reflected in diluted net income (loss) available to common unitholders per unit in the same manner as noted above for net income (loss) available to common stockholders per share.

Fair Value Measurements

The fair value of our financial assets and liabilities are disclosed in Note 16 to our consolidated financial statements. The only financial assets recorded at fair value on a recurring basis in our consolidated financial statements are our marketable securities. We elected not to apply the fair value option for any of our eligible financial instruments or other items.

We determine the estimated fair value of financial assets and liabilities utilizing a hierarchy of valuation techniques based on whether the inputs to a fair value measurement are considered to be observable or unobservable in a marketplace. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect our market assumptions. This hierarchy requires the use of observable market data when available. The following is the fair value hierarchy:


•	Level 1—quoted prices for identical instruments in active markets;


•	Level 2—quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which significant inputs and significant value drivers are observable in active markets; and


•	Level 3—fair value measurements derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.

We determine the fair value for the marketable securities using quoted prices in active markets for identical assets. Our other financial instruments, which are only disclosed at fair value, are comprised of secured debt, unsecured senior notes, unsecured line of credit, unsecured term loan facility and Exchangeable Notes.

We generally determine the fair value of our secured debt, unsecured line of credit, and unsecured term loan facility by performing discounted cash flow analyses using an appropriate market discount rate. We calculate the market rate by obtaining period-end treasury rates for maturities that correspond to the maturities of our fixed-rate debt and then adding an appropriate credit spread based on information obtained from third-party financial institutions. We calculate the market rate of our unsecured line of credit and unsecured term loan facility by obtaining the period-end London Interbank Offered Rate ("LIBOR") rate and then adding an appropriate credit spread based on information obtained from third-party financial institutions. These credit spreads take into account factors, including but not limited to, our credit profile, the tenure of the debt, amortization period, whether the debt is secured or unsecured, and the loan-to-value ratio of the debt to the collateral. These calculations are significantly affected by the assumptions used, including the discount rate, credit spreads, and estimates of future cash flow. We determine the fair value of the liability component of our Exchangeable Notes by performing discounted cash flow analyses using an appropriate market interest rate based upon spreads for our publicly traded debt. We determine the fair value of each of our publicly traded unsecured senior notes based on their quoted trading price at the end of the reporting period, if such prices are available.

Carrying amounts of our cash and cash equivalents, restricted cash, and accounts payable approximate fair value due to their short-term maturities.

Income Taxes

We have elected to be taxed as a REIT under Sections 856 through 860 of the Code. To qualify as a REIT, we must distribute annually at least 90% of our adjusted taxable income, as defined in the Code, to our stockholders and satisfy certain other organizational and operating requirements. For distributions with respect to taxable years ended on or before December 31, 2011, IRS guidance allows REITs to satisfy up to 90% of this requirement through the distribution of shares of common stock, if certain conditions are met. We generally will not be subject to federal income taxes if we distribute 100% of our taxable income for each year to our stockholders. If we fail to qualify as a REIT in any taxable year, we will be subject to federal income taxes (including any applicable alternative minimum tax) on our taxable income at regular corporate rates and we may not be able to qualify as a REIT for four subsequent taxable years. Even if we qualify for taxation as a REIT, we may be subject to certain state and local taxes on our income and property and to federal income taxes and excise taxes on our undistributed taxable income. We believe that we have met all of the REIT distribution and technical requirements for the years ended December 31, 2012, 2011 and 2010, and we were not subject to any federal income taxes (see Note 21). We intend to continue to adhere to these requirements and maintain the Company’s REIT status.

In addition, any taxable income from our taxable REIT subsidiary, which was formed in August 2002, is subject to federal, state, and local income taxes. For the year ended December 31, 2012 the taxable REIT subsidiary had less than $60,000 of taxable income and for the years ended December 31, 2011 and 2010 the taxable REIT subsidiary had less than $30,000 of taxable income.

Uncertain Tax Positions

We include favorable tax positions in the calculation of tax liabilities if it is more likely than not that our adopted tax position will prevail if challenged by tax authorities.

As a result of our REIT status, we are able to claim a dividends-paid deduction on our tax return to deduct the full amount of common and preferred dividends paid to stockholders when computing our annual taxable income. Since this dividends-paid deduction has historically exceeded our taxable income, the Company has historically had significant return of capital to its stockholders. In order for us to be required to record any unrecognized tax benefits or additional tax liabilities, any adjustment for potential uncertain tax positions would need to exceed the return of capital.

We evaluated the potential impact of identified uncertain tax positions for all tax years still subject to potential audit under state and federal income tax law and concluded that our return of capital would not be materially affected for any of the years still subject to potential audit. As of December 31, 2012, the years still subject to audit are 2008 through 2011 under the California state income tax law and 2009 through 2011 under the federal income tax law. We concluded that we did not have any unrecognized tax benefits or any additional tax liabilities as of December 31, 2012 and 2011.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates.

Concentration of Credit Risk

All of our properties and all of our business is currently conducted in the state of California with the exception of the ownership and operation of ten office properties located in the state of Washington. The ability of the tenants to honor the terms of their leases is dependent upon the economic, regulatory, and social factors affecting the communities in which the tenants operate.

As of December 31, 2012, our 15 largest tenants represented approximately 34.1% of total annualized base rental revenues.

We have deposited cash with financial institutions that is insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $250,000 per institution. As of December 31, 2012 and 2011, we had cash accounts in excess of FDIC insured limits.

Recent Accounting Pronouncements

In October 2012, the FASB issued Accounting Standards Update 2012-04, Technical Corrections and Improvements ("ASU 2012-04"), which makes certain technical corrections and “conforming fair value amendments” to the FASB Accounting Standards Codification. The amendments affect various Codification topics and apply to all reporting entities within the scope of those topics. These provisions of the amendment are effective upon issuance, except for amendments that are subject to transition guidance, which will be effective for fiscal periods beginning after December 15, 2012. The provisions of ASU 2012-04 are not expected to have a material impact on our consolidated financial statements.

Effective January 1, 2012, we adopted the provisions of ASU No. 2011-04, Amendment to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRSs ("ASU 2011-04"), which amended ASC Topic 820, Fair Value Measurement. The objective of this guidance is to develop common requirements for measuring fair value and for disclosing information about fair value measurements in accordance with GAAP and International Financial Reporting Standards. The guidance also requires expanded fair value disclosures related to Level 3 financial instruments and Level 3 financial instrument transfers. The guidance does not require any new fair value measurements. The adoption of this guidance did not have a material impact on our consolidated financial statements or notes to our consolidated financial statements.