The accompanying consolidated financial statements include Tripadvisor, our wholly-owned subsidiaries, and entities we control, or in which we have a variable interest and are the primary beneficiary of expected cash profits or losses. All inter-company accounts and transactions have been eliminated in consolidation. Additionally, certain prior period amounts have been reclassified for comparability with the current period presentation. The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). We believe that the assumptions underlying our consolidated financial statements are reasonable. However, these consolidated financial statements do not present our future financial position, the results of our future operations and cash flows.

One of our subsidiaries that operates in China has variable interests in affiliated entities in China in order to comply with Chinese laws and regulations, which restrict foreign investment in internet content provision businesses. Although we do not own the capital stock of these Chinese affiliates, we consolidate their results as we are the primary beneficiary of the cash losses or profits of these variable interest affiliates and have the power to direct the activity of these affiliates. Our variable interest entities’ financial results were not material for all periods presented. Investments in entities in which we do not have a controlling financial interest are accounted for under the equity method, the fair value option, as available-for-sale securities or at cost adjusted for observable price changes and impairments, as appropriate.

We use estimates and assumptions in the preparation of our consolidated financial statements in accordance with GAAP. Our estimates and assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of our consolidated financial statements. These estimates and assumptions also affect the reported amount of net income or loss during any period. Our actual financial results could differ significantly from these estimates. The significant estimates underlying our consolidated financial statements include: (i) recognition and recoverability of goodwill, definite-lived intangibles and other long-lived assets; and (ii) accounting for income taxes.

The COVID-19 pandemic has created and may continue to create significant uncertainty in macroeconomic conditions, which may cause further business disruptions and continue to adversely and materially impact our results of operations. As a result, some of our estimates and assumptions required increased judgment and carry a higher degree of variability and volatility. As events continue to evolve and additional information becomes available, our estimates may change materially in future periods.

Refer to “Note 4: Revenue Recognition” for a discussion about our revenue recognition policies and other financial disclosures.

Cost of revenue consists of expenses that are directly related or closely correlated to revenue generation, including direct costs, such as credit card and other booking transaction payment fees, data center costs, costs associated with prepaid tour tickets, ad serving fees, flight search fees, and other transaction costs. In addition, cost of revenue includes personnel and overhead expenses, including salaries, benefits, stock-based compensation and bonuses for certain customer support personnel who are directly involved in revenue generation.

Selling and marketing expenses primarily consist of direct costs, including traffic generation costs from SEM and other online traffic acquisition costs, syndication costs and affiliate marketing commissions, social media costs, brand advertising (including television and other offline advertising), promotions and public relations. In addition, our sales and marketing expenses consist of indirect costs such as personnel and overhead expenses, including salaries, commissions, benefits, stock-based compensation, and bonuses for sales, sales support, customer support and marketing employees.

We incur advertising costs, consisting of online advertising expense, primarily SEM and other online traffic costs, and offline advertising costs, including television, to promote our brands. We expense the costs associated with communicating the advertisements in the period in which the advertisement takes place. We expense the production costs associated with advertisements in the period in which the advertisement first takes place. For the years ended December 31, 2020, 2019 and 2018, we recorded advertising expense of $118 million, $423 million, and $544 million, respectively, in selling and marketing expense on our consolidated statements of operations. We include prepaid advertising expenses in prepaid expenses and other current assets on our consolidated balance sheet, which were not material as of December 31, 2020 and 2019.

Technology and content expenses consist primarily of personnel and overhead expenses, including salaries and benefits, stock-based compensation expense, and bonuses for salaried employees and contractors engaged in the design, development, testing, content support, and maintenance of our websites and mobile apps. Other costs include licensing, maintenance expense, computer supplies, telecom costs, content translation and localization costs, and consulting costs.

General and administrative expenses consist primarily of personnel and related overhead costs, including personnel engaged in leadership, finance, legal, and human resources, as well as stock-based compensation expense for those same personnel. General and administrative costs also include professional service fees and other fees including audit, legal, tax and accounting, and other costs including bad debt expense, non-income taxes, such as sales, use and other non-income related taxes.

Stock Options. Our employee stock options generally consist of service based awards. The exercise price is equal to the market price of the underlying shares of our common stock at the date of grant. In this regard, when granting stock option awards, our practice is to determine the applicable grant date and to specify that the exercise price shall be the closing price of our common stock on the date of grant. Our stock options generally have a term of ten years from the date of grant and typically vest equally over a four-year requisite service period. We amortize the grant-date fair value of our stock option grants as stock-based compensation expense over the vesting term on a straight-line basis, with the amount of compensation expense recognized at any date at least equaling the portion of the grant-date fair value of the award that is vested at that date.

The estimated grant-date fair value of stock options is calculated using a Black-Scholes Merton option-pricing model (“Black-Scholes model”). The Black-Scholes model incorporates assumptions to fair value stock-based awards, which includes the risk-free rate of return, expected volatility, expected term, and expected dividend yield. Our risk-free interest rate is based on the rates currently available on zero-coupon U.S. Treasury issues, in effect at the time of the grant, whose remaining maturity period most closely approximates the stock option’s expected term assumption. Our expected volatility is calculated by equally weighting the historical volatility and implied volatility on our own common stock. Historical volatility is determined using actual daily price observations of our common stock price over a period equivalent to or approximate to the expected term of our stock option grants to date. Implied volatility represents the volatility calculated from the observed prices of our actively traded options on our common stock. When measuring implied volatility for a specific employee stock option grant we use traded contracts with six month maturities or more and exercise prices approximately equal to the exercise price of the specific option grant. We estimate our expected term using historical exercise behavior and expected post-vest termination data. Our expected dividend yield is zero as we have not historically paid regular cash dividends on our common stock and do not expect to pay regular cash dividends for the foreseeable future.

Restricted Stock Units. Restricted stock units (“RSUs”) are stock awards that are granted to employees entitling the holder to shares of our common stock as the award vests. RSUs are measured at fair value based on the quoted price of our common stock at the date of grant. We amortize the fair value of RSUs as stock-based compensation expense over the vesting term, which is typically over a four-year requisite service period on a straight-line basis, with the amount of compensation expense recognized at any date at least equaling the portion of the grant-date fair value of the award that is vested at that date.

Performance-Based Awards. Performance-based stock options and RSUs vest upon achievement of certain company-based performance conditions and a requisite service period. On the date of grant, the fair value of a performance-based award is calculated using the same method as our service based stock options and RSUs described above. We then assess whether it is probable that the individual performance targets would be achieved. If assessed as probable, compensation expense will be recorded for these awards over the estimated performance period. At each reporting period, we will reassess the probability of achieving the performance targets and the performance period required to meet those targets. The estimation of whether the performance targets will be achieved and of the performance period required to achieve the targets requires judgment, and to the extent actual results or updated estimates differ from our current estimates, the cumulative effect on current and prior periods of those changes will be recorded in the period estimates are revised, or the change in estimate will be applied prospectively depending on whether the change affects the estimate of total compensation cost to be recognized or merely affects the period over which compensation cost is to be recognized. The ultimate number of shares issued and the related compensation expense recognized will be based on a comparison of the final performance metrics to the specified targets.

Market-Based Awards. We issue market-based performance RSUs, or MSUs, which vest upon achievement of specified levels of market conditions. The fair value of our MSUs is estimated at the date of grant using a Monte-Carlo simulation model. The probabilities of the actual number of market-based performance units expected to vest and resultant actual number of shares of common stock expected to be awarded are reflected in the grant date fair values; therefore, the compensation expense for these awards will be recognized assuming the requisite service period is rendered and are not adjusted based on the actual number of awards that ultimately vest.

Estimates of fair value are not intended to predict actual future events or the value ultimately realized by employees who receive these awards, and subsequent events are not indicative of the reasonableness of our original estimates of fair value. The Company accounts for forfeitures in the period in which they occur, rather than estimate expected forfeitures.

We record income taxes under the asset and liability method. Deferred tax assets and liabilities reflect our estimation of the future tax consequences of temporary differences between the carrying amounts of assets and liabilities for book and tax purposes. We determine deferred income taxes based on the differences in accounting methods and timing between financial statement and income tax reporting. Accordingly, we determine the deferred tax asset or liability for each temporary difference based on the enacted income tax rates expected to be in effect when we realize the underlying items of income and expense. We consider all relevant factors when assessing the likelihood of future realization of our deferred tax assets, including our recent earnings experience by jurisdiction, expectations of future taxable income, and the carryforward periods available to us for tax reporting purposes, as well as assessing available tax planning strategies. We may establish a valuation allowance to reduce deferred tax assets to the amount we believe is more likely than not to be realized. Due to inherent complexities arising from the nature of our businesses, future changes in income tax law, tax sharing agreements or variances between our actual and anticipated operating results, we make certain judgments and estimates. Therefore, actual income taxes could materially vary from these estimates. We classify deferred tax assets and liabilities as noncurrent on our consolidated balance sheet.

We record liabilities to address uncertain tax positions we have taken in previously filed tax returns or that we expect to take in a future tax return. The determination for required liabilities is based upon an analysis of each individual tax position, taking into consideration whether it is more likely than not that our tax position, based on technical merits, will be sustained upon examination.

Our cash consists of cash deposits held in global financial institutions. Our cash equivalents consist of highly liquid investments, generally including money market funds, term deposits, and marketable securities, with maturities of 90 days or less at the date of purchase.

For all periods presented, our restricted cash, which primarily consists of escrowed security deposits, was not material and is included in other long-term assets on our consolidated balance sheet.

We classify our marketable securities as either short-term or long-term based on each instrument’s underlying contractual maturity date and as to whether and when we intend to sell a particular security prior to its maturity date. Marketable securities with maturities greater than 90 days at the date of purchase and 12 months or less remaining at the balance sheet date will be classified as short-term and marketable securities with maturities greater than 12 months from the balance sheet date will generally be classified as long-term. We classify our marketable equity securities, limited by policy to money market funds and mutual funds, as either a cash equivalent, short-term or long-term based on the nature of each security and its availability for use in current operations.

Our marketable securities are classified and accounted for as available-for-sale, and therefore are carried at fair value, with unrealized gains and losses, net of taxes, reported in accumulated other comprehensive income (loss) as a component of stockholders’ equity. Fair values are determined for each individual security in the investment portfolio. We determine the appropriate classification of our marketable securities at the time of purchase and reevaluate the designations at each balance sheet date. We invest in highly-rated securities, and our investment policy limits the amount of credit exposure to any one issuer, industry group and currency. The policy requires investments to be investment grade, with the primary objective of minimizing the potential risk of principal loss and providing liquidity of investments sufficient to meet our operating and capital spending requirements and debt repayments. Realized gains and losses on the sale of marketable securities are determined by specific identification of each security’s cost basis. We may sell certain of our marketable securities prior to their stated maturities for strategic reasons including, but not limited to, anticipation of credit deterioration, liquidity, and duration

management. The weighted average maturity of our total invested cash shall not exceed 18 months, and no security shall have a final maturity date greater than three years, according to our investment policy.

We continually review our available for sale securities to determine whether their fair value is below their carrying value. If the fair value of an available for sale security is below their carrying value, and either we intend to sell the security or we will be required to sell before recovery, then the difference between fair value and carrying value is recognized as a loss in other income (expense), net on our consolidated statements of operations. If we do not intend to sell and we will not be required to sell before recovery, then we analyze whether a portion of the unrealized loss is the result of a credit loss. When a portion of the unrealized loss is the result of a credit loss, we recognize an allowance for credit losses on our consolidated balance sheet and a corresponding loss in other income (expense), net on our consolidated statements of operations. Any portion of the unrealized loss on the available for sale securities that is not attributable to a credit loss would be recognized as an unrealized loss in accumulated other comprehensive income (loss) within our consolidated statements of changes in stockholders’ equity.

Accounts receivable are recognized when the right to consideration becomes unconditional and are recorded net of an allowance for credit losses. We record accounts receivable at the invoiced amount. Our customer invoices are generally due 30 days from the time of invoicing. Collateral is not required for accounts receivable. The Company historically recorded an allowance for doubtful accounts using the incurred loss model. Upon adoption of ASC 326 – Financial Instruments – Credit Losses (“ASC 326”), the Company transitioned to the “expected credit loss” methodology in estimating its allowance for credit losses, which the Company adopted on January 1, 2020. Refer to the Recently Adopted Accounting Pronouncements section below, for a detailed accounting discussion on the impact of this new guidance to our accounts receivable and allowance for credit losses, and our accounting policy.

The following table presents the changes in our allowance for credit losses for the periods presented:

	December 31,
	2020			2019			2018
	(in millions)
Allowance for doubtful accounts:
Balance, beginning of period	$	25		$	21		$	16
Provision charged to expense		17			11			11
Write-offs, net of recoveries and other adjustments		(9	)		(7	)		(6	)
Balance, end of period	$	33		$	25		$	21

We record property and equipment at cost, net of accumulated depreciation. We capitalize certain costs incurred during the application development stage related to the development of websites and internal use software when it is probable the project will be completed and the software will be used as intended. Capitalized costs include internal and external costs, if direct and incremental, and deemed by management to be significant. We expense costs related to the planning and post-implementation phases of software and website development as these costs are incurred. Maintenance and enhancement costs (including those costs in the post-implementation stages) are typically expensed as incurred, unless such costs relate to substantial upgrades and enhancements to the website or software resulting in added functionality, in which case the costs are capitalized.

We compute depreciation using the straight-line method over the estimated useful lives of the assets, which is three to five years for computer equipment, capitalized software and website development, office furniture and other equipment. We depreciate leasehold improvements using the straight-line method, over the shorter of the estimated useful life of the improvement or the remaining term of the lease.

We lease office space in a number of countries around the world, generally under non-cancelable operating lease agreements. Our Headquarters Lease is our most significant office space lease and is accounted for as a finance lease under GAAP. The Company has also entered into data center and certain equipment leases, such as network equipment and other leases, which are not material to our consolidated financial statements. Refer to “Note 7: Leases” for a discussion of our lease accounting policy and other financial disclosures.

We account for non-marketable equity investments through which we exercise significant influence but do not have control over the investee under the equity method. Under this method, the investment, originally recorded at cost, is adjusted to recognize the Company’s share of net earnings or losses of the investment as they occur rather than as dividends or other distributions are received. Losses are limited to the extent of the Company’s investment in, advances to and commitments for the investee. In the event we are unable to obtain accurate financial information from the investee in a timely manner, we record our share of earnings or losses of such equity investment on a lag.

Non-marketable equity investments that are not accounted for under the equity method and that do not have a readily determinable fair value are accounted for under the measurement alternative. Under the measurement alternative, the carrying value is measured at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same issuer. Adjustments are determined primarily based on a market approach as of the transaction date. We classify our non-marketable equity investments as long-term assets on our consolidated balance sheet as those investments do not have stated contractual maturity dates.

On a quarterly basis, we perform a qualitative assessment considering impairment indicators to evaluate whether these investments are impaired. Qualitative factors considered include industry and market conditions, financial performance, business prospects, and other relevant events and factors. When indicators of impairment exist, we prepare a quantitative assessment of the fair value of our equity investments, which may include using both the market and income approaches which require judgment and the use of estimates, including discount rates, investee revenues and costs, and available comparable market data of private and public companies, among others. When our assessment indicates that an impairment exists, we measure our non-marketable equity investments at fair value.

Valuations of such privately-held companies are inherently complex and uncertain due to the lack of liquid market for the company’s securities. In addition, such investments are inherently risky in that such companies are typically at an early stage of development, may have no or limited revenues, may not be or may never become profitable, may not be able to secure additional funding or their technologies, services or products may not be successfully developed or introduced into the market.

We account for acquired businesses using the acquisition method of accounting which requires that the tangible assets and identifiable intangible assets acquired and assumed liabilities be recorded at the date of acquisition at their respective fair values. Any excess purchase price over the estimated fair value of the net tangible and intangible assets acquired is allocated to goodwill. When determining the fair values of assets acquired and liabilities assumed, management makes estimates and assumptions, especially with respect to intangible assets. Significant estimates in valuing certain intangible assets may include but are not limited to future expected cash flows from customer and supplier relationships, acquired technology and trade names from a market participant perspective, useful lives and discount rates. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. Valuations are performed by management or third party valuation specialists under management's supervision, where appropriate. Any changes to provisional amounts identified during the measurement period, calculated as if the accounting had been completed as of the acquisition date, are recognized in the consolidated financial statements in the reporting period in which the adjustment amounts are determined.

We assess goodwill, which is not amortized, for impairment annually during the fourth quarter, or more frequently, if events and circumstances indicate impairment may have occurred. We test goodwill for impairment at the reporting unit level. Goodwill is assigned to reporting units that are expected to benefit from the synergies of the business combination as of the acquisition date. We evaluate our reporting units when changes in our operating structure occur, and if necessary, reassign goodwill using a relative fair value allocation approach. Once goodwill has been allocated to the reporting units, it no longer retains its identification with a particular acquisition and becomes identified with the reporting unit in its entirety. Accordingly, the fair value of the reporting unit as a whole is available to support the recoverability of its goodwill.

The Company has the option to qualitatively assess whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. In the evaluation of goodwill for impairment, we generally first perform a qualitative assessment to determine whether it is more likely than not (i.e., a likelihood of more than 50%) that the estimated fair value of the reporting unit is less than the carrying amount. Periodically, we may choose to forgo the initial qualitative assessment and proceed directly to a quantitative analysis to assist in our annual evaluation. When assessing goodwill for impairment, our decision to perform a qualitative impairment assessment for an individual reporting unit in a given year is influenced by a number of factors, including, but not limited to the size of the reporting unit's goodwill, the significance of the excess of the reporting unit's estimated fair value over carrying value at the last quantitative assessment date, the amount of time in between quantitative fair value assessments from the date of acquisition to establish an updated baseline quantitative analysis, and other performance and market indicators. During a qualitative assessment, if we determine that it is not more likely than not that the implied fair value of the goodwill is less than its carrying amount, no further testing is necessary. If, however, we determine that it is more likely than not that the implied fair value of the goodwill is less than its carrying amount, we then perform a quantitative assessment and compare the estimated fair value of the reporting unit to the carrying value. If the carrying value of a reporting unit exceeds its estimated fair value, the goodwill impairment is measured using the difference between the carrying value and the fair value of the reporting unit; however, any loss recognized cannot exceed the total amount of goodwill allocated to that reporting unit.

In determining the estimated fair values of reporting units in a quantitative goodwill impairment test, we generally use a blend, of the following recognized valuation methods: the income approach (discounted cash flows model) and the market valuation approach, which we believe compensates for the inherent risks of using either model on a stand-alone basis. The discounted cash flows model indicates the fair value of the reporting units based on the present value of the cash flows that we expect the reporting units to generate in the future. Our significant estimates in the discounted cash flows model include: weighted average cost of capital; long-term rate of growth and profitability of the reporting unit; income tax rates and working capital effects. The market valuation approach indicates the fair value of the business based on a comparison to comparable publicly traded firms in similar lines of business and other precedent transactions. Our significant estimates in the market approach model include identifying similar companies with comparable business factors such as size, growth, profitability, risk and return on investment and assessing comparable revenue and/or income multiples in estimating the fair value of the reporting units. Valuations are performed by management or third party valuation specialists under management's supervision, where appropriate. We believe that the estimated fair values assigned to our reporting units in impairment tests are based on reasonable assumptions that marketplace participants would use. However, such assumptions are inherently uncertain and actual results could differ from those estimates. The use of different assumptions, estimates or judgments could trigger the need for an impairment charge, or materially increase or decrease the amount of any such impairment charge.

Intangible assets with estimable useful lives, or definite-lived intangibles, are carried at cost and are amortized on a straight-line basis over their estimated useful lives and reviewed for impairment upon certain triggering events. We routinely review the remaining estimated useful lives of definite-lived intangible assets. If we reduce the estimated useful life assumption, the remaining unamortized balance is amortized over the revised estimated useful life.

Intangible assets that have indefinite lives are not amortized and are tested for impairment annually during the fourth quarter, or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. Similar to the qualitative assessment for goodwill, we may assess qualitative factors to determine if it is more likely than not that the implied fair value of the indefinite-lived intangible asset is less than its carrying amount. If we determine that it is not more likely than not that the implied fair value of the indefinite-lived intangible asset is less than its carrying amount, no further testing is necessary. If, however, we determine that it is more likely than not that the implied fair value of the indefinite-lived intangible asset is less than its carrying amount, we compare the implied fair value of the indefinite-lived asset with its carrying amount. If the carrying amount of an individual indefinite-lived intangible asset exceeds its implied fair value, the individual asset is written down by an amount equal to such excess. The assessment of qualitative factors is optional and at our discretion. We may bypass the qualitative assessment for any indefinite-lived intangible asset in any period and resume performing the qualitative assessment in any subsequent period. We base our quantitative measurement of fair value of indefinite-lived intangible assets, using the relief-from-royalty method. This method assumes that the trade name and trademarks have value to the extent that their owner is relieved of the obligation to pay royalties for the benefits received from them. This method requires us to estimate future revenues, the appropriate royalty rate and the weighted average cost of capital, however, such assumptions are inherently uncertain and actual results could differ from those estimates. The use of different assumptions, estimates or judgments could trigger the need for an impairment charge, or materially increase or decrease the amount of any such impairment charge.

We periodically review the carrying amount of our definite-lived intangible assets and other long-term assets, including property and equipment and website and internal use software, to determine whether current events or circumstances indicate that such carrying amounts may not be recoverable. Factors that would necessitate an impairment assessment include a significant adverse change in the extent or manner in which an asset is used, a significant adverse change in legal factors or the business climate that could affect the value of the asset, or a significant decline in the observable market value of an asset, among others. If such facts indicate a potential impairment, we assess the recoverability of the asset group by determining if the carrying value of the asset group exceeds the sum of the projected undiscounted cash flows expected to result from the use and eventual disposition of the assets over the remaining economic life of the primary asset of the group. If the recoverability test indicates that the carrying value of the asset group is not recoverable, we will estimate the fair value of the asset group using appropriate valuation methodologies which would typically include an estimate of discounted cash flows, using an appropriate discount rate. Any impairment would be measured by the amount that the carrying values, of such asset groups, exceed their fair value and would be included in operating income on the consolidated statement of operations. Considerable management judgment is necessary to estimate the fair value of asset groups. Accordingly, actual results could vary significantly from such estimates. We have not identified any circumstances that would warrant an impairment charge for any recorded definite-lived intangibles or other long term assets on our consolidated balance sheet at December 31, 2020 or 2019.

In our Experiences and Rentals free-to-list offerings, we generally receive cash from travelers at the time of booking and we record these amounts, net of our commissions, on our consolidated balance sheets as deferred merchant payables. We pay the suppliers, generally the third-party experience providers and vacation rental owners, after the travelers’ use. Therefore, we receive cash from the traveler prior to paying the supplier and this operating cycle represents a working capital source or use of cash to us. Our deferred merchant payables balance was $36 million and $159 million at December 31, 2020 and 2019, respectively, on our consolidated balance sheets. Refer to

“Note 1: Organization and Business Description” and “Note 4: Revenue Recognition” for further discussion of the impact COVID-19 had on our deferred merchant payables balance in our consolidated financial statements.

We account for derivative instruments that do not qualify for hedge accounting as either assets or liabilities and carry them at fair value, with any subsequent adjustments to fair value recorded in other income (expense), net on our consolidated statements of operations. Monetary assets and liabilities denominated in a currency other than the functional currency of a given subsidiary are remeasured at spot rates in effect on the balance sheet date with the effects of changes in foreign currency exchange rates reported in other income (expense), net on our consolidated statements of operations. In certain circumstances, we enter into forward contracts to reduce, to the extent practical, our potential exposure to the effects of fluctuating foreign currency exchange rates on our cash flows denominated in foreign currencies. Accordingly, fair value changes in the forward contracts help mitigate the changes in the value of the remeasured assets and liabilities attributable to changes in foreign currency exchange rates, except to the extent of the spot-forward differences. These differences are not expected to be significant due to the short-term nature of the contracts, which to date, have typically had maturities at inception of 90 days or less. The net cash received or paid related to our derivative instruments are classified in other investing activities in our consolidated statements of cash flows. Counterparties to forward contracts consist of major international financial institutions. We monitor our positions and the credit ratings of the counterparties involved and, by policy limits, the amount of credit exposure to any one party. We do not use derivatives for trading or speculative purposes. We did not enter into any cash flow, fair value or net investment hedges as of December 31, 2020 or 2019. Refer to “Note 5: Financial Instruments and Fair Value Measurements” for additional information on derivatives.

Our consolidated financial statements are reported in U.S. dollars. Certain of our subsidiaries outside of the U.S. use the related local currency as their functional currency and not the U.S. dollar. Therefore assets and liabilities of our foreign subsidiaries are translated at the spot rate in effect at the applicable reporting date, and the consolidated statements of operations are translated at the average exchange rates in effect during the applicable reporting period. The resulting unrealized cumulative translation adjustment is recorded as a component of accumulated other comprehensive income (loss) in stockholders’ equity on our consolidated balance sheet.

We also have subsidiaries that have transactions in currencies other than their functional currency. Transactions denominated in currencies other than the functional currency are recorded based on foreign currency exchange rates at the time such transactions arise. Subsequent changes in foreign currency exchange rates result in transaction gains and losses which are reflected in our consolidated statements of operations as unrealized (based on the applicable period-end exchange rate) or realized upon settlement of the transactions. Accordingly, we have recorded a net foreign currency exchange gain of $5 million for the year ended December 31, 2020, and net losses of $2 million and $9 million for the years ended December 31, 2019 and 2018, respectively, in other income (expense), net on our consolidated statement of operations. These amounts also include transaction gains and losses, both realized and unrealized from forward contracts.

We apply fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. We measure assets and liabilities at fair value based on the expected exit price, which is the amount that would be received on the sale of an asset or amount paid to transfer a liability, as the case may be, in an orderly transaction between market participants in the principal or most advantageous market in which we would transact. As such, fair value may be based on assumptions that market participants would use in pricing an asset or liability at the measurement date. The authoritative guidance on fair value measurements establishes a consistent framework for measuring fair value on either a recurring or nonrecurring basis whereby inputs, used in valuation techniques, are assigned a hierarchical level. GAAP provides the following hierarchical levels of inputs used to measure fair value:

Level 1—Valuations are based on quoted market prices for identical assets and liabilities in active markets.

Level 2—Valuations are based on observable inputs other than quoted market prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data.

Level 3—Valuations are based on unobservable inputs reflecting our own assumptions, consistent with reasonably available assumptions made by other market participants. These valuations require significant judgment.

We defer costs we incur to issue debt, which are presented in the balance sheet as a direct deduction from the carrying amount of the related debt liability, and amortize these costs using the effective interest rate method to interest expense over the term of the debt. We also defer costs we incur to enter into or amend a revolving credit facility, which are presented in the balance sheet as a long-term asset, and amortize these costs using the effective interest rate method to interest expense over the term of the credit facility.

In addition to the impact of COVID-19, which is discussed in “Note 1: Organization and Business Description”, our business is subject to certain risks and concentrations, including a concentration related to dependence on our relationships with our customers. For the years ended December 31, 2020, 2019 and 2018 our two most significant travel partners, Expedia (and its subsidiaries) and Booking (and its subsidiaries), each accounted for 10% or more of our consolidated revenue and combined accounted for 25%, 33% and 37%, respectively, of our consolidated revenue, with nearly all of this revenue concentrated in our Hotels, Media & Platform segment. Refer to “Note 4: Revenue Recognition” and “Note 20: Segment and Geographic Information” for information regarding other concentrations related to geographic and product revenues.

Financial instruments, which potentially subject us to concentration of credit risk at any point in time, generally consist, at any point in time, primarily of cash and cash equivalents, corporate debt securities, forward contracts, and accounts receivable. We maintain some cash and cash equivalents balances with financial institutions that are in excess of Federal Deposit Insurance Corporation insurance limits. Our cash and cash equivalents are primarily composed of bank account balances with financial institutions primarily denominated in U.S. dollars, Euros, British pounds, and Australian dollars. We invest in highly-rated corporate debt securities, and our investment policy limits the amount of credit exposure to any one issuer, industry group and currency. Our credit risk related to corporate debt securities is also mitigated by the relatively short maturity period required by our investment policy. Forward contracts are transacted with major international financial institutions with high credit standings, which to date, have typically had maturities of less than 90 days. Our overall credit risk related to accounts receivable is mitigated by the relatively short collection period.

Periodically, we review the status of all significant outstanding matters to assess any potential financial exposure. When (i) it is probable that an asset has been impaired or a liability has been incurred and (ii) the amount of the loss can be reasonably estimated, we record the estimated loss in our consolidated statements of operations. We provide disclosure in the notes to the consolidated financial statements for loss contingencies that do not meet both these conditions if there is a reasonable possibility that a loss may have been incurred that would be material to the consolidated financial statements. Significant judgment may be required to determine the probability that a liability has been incurred and whether such liability is reasonably estimable. We base accruals made on the best information available at the time which can be highly subjective. The final outcome of these matters could vary significantly from the amounts included in the accompanying consolidated financial statements.

Shares of our common stock repurchased are recorded at cost as treasury stock and result in the reduction of stockholders' equity in our consolidated balance sheet. We may reissue these treasury shares. When treasury shares

are reissued, we use the average cost method for determining the cost of reissued shares. If the issuance price is higher than the cost, the excess of the issuance price over the cost is credited to additional paid-in-capital. If the issuance price is lower than the cost, the difference is first charged against any credit balance in additional paid-in-capital from the previous issuances of treasury stock and any remaining balance is charged to retained earnings.

Refer to “Note 17: Earnings Per Share” for a discussion as to how we compute Basic EPS and Diluted EPS.

In June 2016, the FASB issued new accounting guidance which replaced the incurred loss impairment model with an expected loss methodology on the measurement of credit losses for financial assets measured at amortized cost, which includes accounts receivable, notes receivable, and available for sale securities. For financial assets measured at amortized cost, this new guidance requires an entity to: (1) estimate its lifetime expected credit losses upon recognition of the financial assets and establish an allowance to present the net amount expected to be collected; (2) recognize this allowance and changes in the allowance during subsequent periods through net income; and (3) consider relevant information about past events, current conditions and reasonable and supportable forecasts in assessing the lifetime expected credit losses. For available for sale securities, this new guidance made several targeted amendments to the existing other-than-temporary impairment model, including: (1) requiring disclosure of the allowance for credit losses; (2) allowing reversals of the previously recognized credit losses until the entity has the intent to sell, is more-likely-than-not required to sell the securities, or the maturity of the securities; (3) limiting impairment to the difference between the amortized cost basis and fair value; and (4) not allowing entities to consider the length of time that fair value has been less than amortized cost as a factor in evaluating whether a credit loss exists. In addition, ASC 326 made changes to the accounting for available for sale securities. One such change is to require credit losses to be presented as an allowance rather than as a write-down on available for sale securities management does not intend to sell or believes that it is more likely than not they will be required to sell.

The Company adopted ASC 326 on January 1, 2020, using a modified retrospective transition method for all financial assets measured at amortized cost, which requires a cumulative-effect adjustment of initial application, if any, to be recognized on the date of adoption. The cumulative-effect adjustment recorded by the Company on January 1, 2020 to retained earnings on its consolidated balance sheet was $3 million. Financial results for reporting periods beginning after January 1, 2020 are presented under the new guidance, while prior period amounts are not adjusted and continue to be reported in accordance with previous GAAP. Credit loss estimates on accounts receivable are recorded in general and administrative expenses on our consolidated statement of operations. Credit loss estimates on available for sale securities are recorded in interest expense on our consolidated statement of operations. The Company has updated its significant accounting policies as described below as of January 1, 2020.

Accounts Receivable and Allowance for Credit Losses. The Company historically recorded an allowance for doubtful accounts using the incurred loss model. Upon adoption of ASC 326, the Company transitioned to the “expected credit loss” methodology in estimating its allowance for credit losses.

We apply the “expected credit loss” methodology by first assessing our historical losses based on credit sales and then adding in an assessment of expected changes in the foreseeable future, whether positive or negative, to the Company’s ability to collect its outstanding accounts receivables, or the expectation for future losses. The Company develops its expectation for future losses by assessing the profiles of its customers using their historical payment patterns, any known changes to those customers’ ability to fulfill their payment obligations, and assessing broader economic conditions that may impact our customers’ ability to pay their obligations. Where appropriate, the Company performs this analysis using a portfolio approach. Portfolios comprise customers with similar characteristics and payment history, and we have concluded that the aggregation of these customers into various portfolios does not produce a result that is materially different from considering the affected customers individually. Customers are assigned internal credit ratings, as determined by the Company, based on our collection profiles. Customers whose outstanding obligations are less likely to experience a credit loss are assigned a higher internal

credit rating, and those customers whose outstanding obligations are more likely to experience a credit loss are assigned a lower credit rating. We recognize a greater credit loss allowance on the accounts receivable due from those customers in the lower credit tranche, as determined by the Company. When the Company becomes aware of facts and circumstances affecting an individual customer, it also takes that specific customer information into account as part of its calculation of expected credit losses.

The Company's exposure to credit losses may increase if our customers are adversely affected by changes in macroeconomic pressures or uncertainty associated with local or global economic recessions, including the economic impact to our customers associated with COVID-19, or other customer-specific factors.

Available for sale securities. The Company's investment portfolio at any point in time may contain investments, including, in U.S. treasury and U.S. government agency securities, taxable and tax-exempt municipal notes, corporate notes and bonds, commercial paper, non-U.S. government agency securities, term deposits, and money market funds. The Company segments its portfolio based on the underlying risk profiles of the securities and has a zero loss expectation for U.S. treasury and U.S. government agency securities. The Company regularly reviews the securities in an unrealized loss position and evaluates the expected credit loss risk by considering factors such as historical experience, market data, issuer-specific factors, and current economic conditions. As of December 31, 2020 and 2019, the Company had no available for sale securities.

As of December 31, 2020, there are no other newly issued accounting standards expected to have a material impact on the Company’s financial statements or disclosures.