Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and pursuant to Article 10 of Regulation S‑X of the Securities Act of 1933, as amended (the “Securities Act”). Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows. Interim-period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The condensed balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all disclosures required by U.S. GAAP for complete financial statements. Because all of the disclosures required by U.S. GAAP for complete financial statements are not included herein, these unaudited condensed consolidated financial statements and the notes accompanying them should be read in conjunction with the Company’s audited consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2019 filed on March 30, 2020 with the Securities and Exchange Commission. The accompanying consolidated financial statements have been prepared in accordance with U.S. GAAP and include the consolidated accounts of the Company and its wholly-owned subsidiary, RAPT Therapeutics Australia Pty Ltd., which was established in 2018. All intercompany balances and transactions have been eliminated in consolidation. Revenue License and collaborative agreement revenue consists of license, milestone and royalty payments generated through agreements with strategic partners for the development and commercialization of certain product candidates. The terms of an agreement may include a non-refundable upfront fee, payments based upon achievement of milestones and royalties on net product sales. If a portion of the nonrefundable upfront fee or other payments received is allocated to continuing performance obligations under the terms of an agreement, such portion is recorded as deferred revenue and recognized as revenue when or as the underlying performance obligation is satisfied. The Company recognizes revenue when it transfers promised goods or services to customers or counterparties in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. In determining the appropriate amount of revenue to be recognized, the Company performs the following steps: (i) identification of the promised goods or services in the agreement; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the agreement; (iii) measurement of the transaction price, including any constraint on variable consideration; (iv) allocation of the transaction price to performance obligations based on estimated selling prices; and (v) recognition of revenue when or as the Company satisfies each performance obligation. Licenses: If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in an agreement, the Company will recognize revenue from the nonrefundable, upfront fee allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. If a license is bundled with other performance obligations, the Company utilizes judgment to assess the nature of the combined performance obligations to determine whether the combined performance obligations are satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone payments: If an agreement includes event-based or milestone payments, the Company evaluates whether the events or milestones are considered likely to be achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is unlikely that a significant revenue reversal would occur, the value of the associated event-based or milestone payments is included in the transaction price. Event-based or milestone payments that are not within the control of the Company are not included in the transaction price until they become likely to be achieved. Royalties: If an agreement includes sales-based royalties and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied. Stock-Based Compensation The Company measures stock-based compensation expense for all employee and non-employee stock-based awards based on their grant date fair value using the Black-Scholes option-pricing model. Subsequent to the adoption of ASU 2018-07, Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, stock-based compensation expense for non-employee stock-based awards is also measured based on the grant date fair value with the estimated fair value expensed over the period for which the non-employee is required to provide service in exchange for the award. For stock-based awards with service conditions only, stock-based compensation expense is recognized over the requisite service period using the straight-line method. For awards with performance conditions, the Company evaluates the probability of achieving performance conditions at each reporting date. The Company recognizes stock-based compensation expense using an accelerated attribution method when it is deemed probable that the performance condition will be met. Forfeitures are recognized as they occur. Stock-based compensation expense related to restricted stock awards is determined using the estimated fair value of the Company’s common stock on the date of grant for the period prior to the Company’s initial public offering (“IPO”) in November 2019. The fair value of restricted stock awards granted after the IPO is determined based on the stock price on the date of grant. The estimated fair value is amortized as compensation expense over the service period of the award. Stock-based compensation expense related to the Company’s employee stock purchase plan is recognized based on the fair value of each award estimated on the first day of the offering period using the Black‑Scholes option-pricing model and recorded as expense over the service period using the straight‑line method. Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the number of potential dilutive securities outstanding during the period calculated in accordance with the treasury stock method. Diluted net loss per share is the same as basic net loss per share for all periods presented since the effect of including potential dilutive securities is anti-dilutive. Marketable securities Marketable securities primarily consist of commercial paper, corporate bonds and U.S. government agency securities. The Company has classified its marketable securities as available-for-sale and may sell these securities prior to their stated maturities. The Company views these marketable securities as available to support current operations and classifies marketable securities with maturities beyond 12 months as current assets. The Company’s marketable securities are carried at estimated fair value, which is derived from independent pricing sources based on quoted prices in active markets for similar securities. Unrealized gains and losses are reported as a component of accumulated other comprehensive loss, net of tax. The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in other income, net on the condensed consolidated statements of operations. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (the “FASB”) or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on our condensed consolidated financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended (the “JOBS Act”), the Company meets the definition of an emerging growth company and has elected the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act. Adopted Accounting Pronouncements In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Non-Employee Share-Based Payment Accounting as part of the FASB’s simplification initiative. ASU 2018‑07 expands the scope of Topic 718 and allows the application of the requirements of Topic 718 to certain non-employee awards to acquire goods and services from non‑employees. The Company adopted ASU 2018‑07 in the first quarter of 2020 using a modified retrospective method and there was an insignificant impact to the Company’s financial position and results of operations related to this adoption. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurements (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement as part of the FASB’s disclosure framework project. ASU 2018-13 removes certain disclosure requirements, including the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, the policy for timing of transfers between levels and the valuation process for Level 3 fair value measurements. This ASU also modifies existing disclosure requirements by clarifying that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date and adds disclosure requirements over Level 3 fair value measurements. The Company adopted ASU 2018-13 in the first quarter of 2020 and there was no impact to the Company’s financial position or results of operations related to this adoption. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. ASU 2019-12 also improves the consistent application, and the simplification, of other areas of Topic 740 by clarifying and amending existing guidance. The Company adopted ASU 2019-12 in the fourth quarter of 2019 and there was no impact to the financial position or results of operations related to this adoption. Recently Issued Accounting Pronouncement Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases. ASU 2016-02 requires lessees to record most leases on their balance sheet while recognizing expense in a manner similar to the accounting under the original lease guidance (Topic 840). ASU 2016‑02 states that a lessee would recognize a lease liability for the obligation to make lease payments and a right-to-use asset for the right to use the underlying asset for the lease term. ASU 2016-02 is effective for the Company’s fiscal year beginning after December 15, 2021 and early adoption is permitted. The Company is currently assessing the timing of adoption of ASU 2016-02 and the impact that adoption will have on its consolidated financial statements and related disclosures. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 amended guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities. For available-for-sale debt securities, credit losses will be presented as an allowance rather than as a write-down. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, to increase awareness of the amendments and to expedite improvements to Topic 326. In May 2019, the FASB issued ASU No. 2019-05, Financial Instruments—Credit Losses, Topic 326, providing companies with an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. These ASUs do not change the core principle of the guidance in ASU 2016-13; instead, these amendments are intended to clarify and improve operability of certain topics. In November 2019, the FASB issued ASU No. 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates and ASU No. 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, which defer the effective date of the new credit loss standard. ASU 2016-13 and its related amendments are effective for the Company’s fiscal year beginning after December 15, 2022 and early adoption is permitted. The Company is currently assessing the timing of adoption of ASU 2016-13 and the impact that adoption will have on its consolidated financial statements and related disclosures.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2020

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and pursuant to Article 10 of Regulation S‑X of the Securities Act of 1933, as amended (the “Securities Act”). Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows. Interim-period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The condensed balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all disclosures required by U.S. GAAP for complete financial statements. Because all of the disclosures required by U.S. GAAP for complete financial statements are not included herein, these unaudited condensed consolidated financial statements and the notes accompanying them should be read in conjunction with the Company’s audited consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2019 filed on March 30, 2020 with the Securities and Exchange Commission.

The accompanying consolidated financial statements have been prepared in accordance with U.S. GAAP and include the consolidated accounts of the Company and its wholly-owned subsidiary, RAPT Therapeutics Australia Pty Ltd., which was established in 2018. All intercompany balances and transactions have been eliminated in consolidation.

Revenue

License and collaborative agreement revenue consists of license, milestone and royalty payments generated through agreements with strategic partners for the development and commercialization of certain product candidates. The terms of an agreement may include a non-refundable upfront fee, payments based upon achievement of milestones and royalties on net product sales. If a portion of the nonrefundable upfront fee or other payments received is allocated to continuing performance obligations under the terms of an agreement, such portion is recorded as deferred revenue and recognized as revenue when or as the underlying performance obligation is satisfied.

The Company recognizes revenue when it transfers promised goods or services to customers or counterparties in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. In determining the appropriate amount of revenue to be recognized, the Company performs the following steps: (i) identification of the promised goods or services in the agreement; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the agreement; (iii) measurement of the transaction price, including any constraint on variable consideration; (iv) allocation of the transaction price to performance obligations based on estimated selling prices; and (v) recognition of revenue when or as the Company satisfies each performance obligation.

Licenses: If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in an agreement, the Company will recognize revenue from the nonrefundable, upfront fee allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. If a license is bundled with other performance obligations, the Company utilizes judgment to assess the nature of the combined performance obligations to determine whether the combined performance obligations are satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

Milestone payments: If an agreement includes event-based or milestone payments, the Company evaluates whether the events or milestones are considered likely to be achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is unlikely that a significant revenue reversal would occur, the value of the associated event-based or milestone payments is included in the transaction price. Event-based or milestone payments that are not within the control of the Company are not included in the transaction price until they become likely to be achieved.

Royalties: If an agreement includes sales-based royalties and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied.

Stock-Based Compensation

The Company measures stock-based compensation expense for all employee and non-employee stock-based awards based on their grant date fair value using the Black-Scholes option-pricing model. Subsequent to the adoption of ASU 2018-07, Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, stock-based compensation expense for non-employee stock-based awards is also measured based on the grant date fair value with the estimated fair value expensed over the period for which the non-employee is required to provide service in exchange for the award. For stock-based awards with service conditions only, stock-based compensation expense is recognized over the requisite service period using the straight-line method. For awards with performance conditions, the Company evaluates the probability of achieving performance conditions at each reporting date. The Company recognizes stock-based compensation expense using an accelerated attribution method when it is deemed probable that the performance condition will be met. Forfeitures are recognized as they occur.

Stock-based compensation expense related to restricted stock awards is determined using the estimated fair value of the Company’s common stock on the date of grant for the period prior to the Company’s initial public offering (“IPO”) in November 2019. The fair value of restricted stock awards granted after the IPO is determined based on the stock price on the date of grant. The estimated fair value is amortized as compensation expense over the service period of the award.

Stock-based compensation expense related to the Company’s employee stock purchase plan is recognized based on the fair value of each award estimated on the first day of the offering period using the Black‑Scholes option-pricing model and recorded as expense over the service period using the straight‑line method.

Net Loss Per Share

Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the number of potential dilutive securities outstanding during the period calculated in accordance with the treasury stock method. Diluted net loss per share is the same as basic net loss per share for all periods presented since the effect of including potential dilutive securities is anti-dilutive.

Marketable securities

Marketable securities primarily consist of commercial paper, corporate bonds and U.S. government agency securities. The Company has classified its marketable securities as available-for-sale and may sell these securities prior to their stated maturities. The Company views these marketable securities as available to support current operations and classifies marketable securities with maturities beyond 12 months as current assets. The Company’s marketable securities are carried at estimated fair value, which is derived from independent pricing sources based on quoted prices in active markets for similar securities. Unrealized gains and losses are reported as a component of accumulated other comprehensive loss, net of tax. The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in other income, net on the condensed consolidated statements of operations.

Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (the “FASB”) or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on our condensed consolidated financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended (the “JOBS Act”), the Company meets the definition of an emerging growth company and has elected the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act.

Adopted Accounting Pronouncements

In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Non-Employee Share-Based Payment Accounting as part of the FASB’s simplification initiative. ASU 2018‑07 expands the scope of Topic 718 and allows the application of the requirements of Topic 718 to certain non-employee awards to acquire goods and services from non‑employees. The Company adopted ASU 2018‑07 in the first quarter of 2020 using a modified retrospective method and there was an insignificant impact to the Company’s financial position and results of operations related to this adoption.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurements (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement as part of the FASB’s disclosure framework project. ASU 2018-13 removes certain disclosure requirements, including the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, the policy for timing of transfers between levels and the valuation process for Level 3 fair value measurements. This ASU also modifies existing disclosure requirements by clarifying that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date and adds disclosure requirements over Level 3 fair value measurements. The Company adopted ASU 2018-13 in the first quarter of 2020 and there was no impact to the Company’s financial position or results of operations related to this adoption.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. ASU 2019-12 also improves the consistent application, and the simplification, of other areas of Topic 740 by clarifying and amending existing guidance. The Company adopted ASU 2019-12 in the fourth quarter of 2019 and there was no impact to the financial position or results of operations related to this adoption.

Recently Issued Accounting Pronouncement Not Yet Adopted

In February 2016, the FASB issued ASU No. 2016-02, Leases. ASU 2016-02 requires lessees to record most leases on their balance sheet while recognizing expense in a manner similar to the accounting under the original lease guidance (Topic 840). ASU 2016‑02 states that a lessee would recognize a lease liability for the obligation to make lease payments and a right-to-use asset for the right to use the underlying asset for the lease term. ASU 2016-02 is effective for the Company’s fiscal year beginning after December 15, 2021 and early adoption is permitted. The Company is currently assessing the timing of adoption of ASU 2016-02 and the impact that adoption will have on its consolidated financial statements and related disclosures.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 amended guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities. For available-for-sale debt securities, credit losses will be presented as an allowance rather than as a write-down. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, to increase awareness of the amendments and to expedite improvements to Topic 326. In May 2019, the FASB issued ASU No. 2019-05, Financial Instruments—Credit Losses, Topic 326, providing companies with an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. These ASUs do not change the core principle of the guidance in ASU 2016-13; instead, these amendments are intended to clarify and improve operability of certain topics. In November 2019, the FASB issued ASU No. 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates and ASU No. 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, which defer the effective date of the new credit loss standard. ASU 2016-13 and its related amendments are effective for the Company’s fiscal year beginning after December 15, 2022 and early adoption is permitted. The Company is currently assessing the timing of adoption of ASU 2016-13 and the impact that adoption will have on its consolidated financial statements and related disclosures.