Cash, Cash Equivalents and Investments

The Company's cash, cash equivalents and investments as of September 30, 2021 and December 31, 2020 consisted primarily of cash, U.S. government securities, corporate bonds, commercial paper, certificates of deposit and money market funds.

The Company classifies investments as available-for-sale at the time of purchase and reevaluates such classification as of each balance sheet date. All investments are recorded at estimated fair value. Unrealized gains and losses on available-for-sale investments are included in accumulated other comprehensive income (loss), a component of stockholders' equity. If the Company does not expect to recover the entire amortized cost basis of the available-for-sale debt security, it considers the available-for-sale debt security to be impaired. For individual debt securities classified as available-for-sale and deemed impaired, the Company assesses whether such decline has resulted from a credit loss or other factors. Impairment relating to credit losses is recorded through a reserve, limited to the amount that the fair value is less than the amortized cost basis. Impairment deemed to be non-credit related is reported in other income (expense), net in the condensed consolidated statements of comprehensive loss. Realized gains and losses are determined based on the specific identification method and are reported in other income (expense), net in the condensed consolidated statements of comprehensive loss. Interest, amortization of premiums and accretion of discount on all investments classified as available-for-sale are also included as a component of other income (expense), net in the condensed consolidated statements of comprehensive loss. Based on the Company's assessment, no impairments for credit losses were recognized during the three months ended September 30, 2021 or September 30, 2020.

As of September 30, 2021 and December 31, 2020, the Company's cash was $93.6 million and $173.2 million, respectively.

A summary of the Company's cash equivalents and investments as of September 30, 2021 is as follows:


Cash Equivalents:	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Money market funds	$	176,144	$	—	$	—	$	176,144
Certificates of deposit	25,076		—		—		25,076

	$	201,220	$	—	$	—	$	201,220
Investments:	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate bonds and commercial paper	$	36,472	$	3	$	(9)	$	36,466
Certificates of deposit	12,161		—		—		12,161
U.S. government securities	51,185		3		(10)		51,178
	$	99,818	$	6	$	(19)	$	99,805

A summary of the Company's cash equivalents and investments as of December 31, 2020 is as follows:


Cash Equivalents:	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Money market funds	$	188,469	$	—	$	—	$	188,469
Certificates of deposit	25,028		—		—		25,028
Corporate bonds and commercial paper	997		—		(1)		996
U.S. government securities	19,999		—		—		19,999
	$	234,493	$	—	$	(1)	$	234,492
Investments:	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate bonds and commercial paper	$	31,233	$	15	$	(9)	$	31,239
Certificates of deposit	10,007		—		—		10,007
U.S. government securities	90,120		—		(14)		90,106
	$	131,360	$	15	$	(23)	$	131,352

The Company may sell its investments at any time, without significant penalty, for use in current operations or for other purposes, even if they have not yet reached maturity. As a result, the Company classifies its investments, including investments with maturities beyond twelve months, as current assets in the accompanying condensed consolidated balance sheets.

The following table summarizes the estimated fair value of the Company's investments, designated as available-for-sale and classified by the contractual maturity date of the investments as of the dates shown:


	September 30, 2021		December 31, 2020
Due within one year or less	$	77,598	$	131,352
Due after one year through five years	22,207		—
	$	99,805	$	131,352

The Company has certain available-for-sale investments in a gross unrealized loss position, all of which have been in such position for less than twelve months. The Company regularly reviews its investments for impairment resulting from credit loss using both qualitative and quantitative criteria, as necessary, based on the composition of the portfolio at period end. The Company considers factors such as the length of time and extent to which the market value has been less than the cost, the financial position and near-term prospects of the issuer and its intent to sell, or whether it is more likely than not the Company will be required to sell the investment before recovery of the investment's amortized-cost basis. If the Company determines that impairment exists in one of these investments, the respective investment would be written down to fair value. For debt securities, the portion of the write-down related to credit loss would be recognized in other income, net in the condensed consolidated statements of comprehensive loss if the intent of the Company was to sell the investment before recovery. If the Company did not intend to sell, the portion of the write-down related to credit loss would be recorded to a reserve. Any portion

not related to credit loss would be included in accumulated other comprehensive income (loss) in the condensed consolidated statements of comprehensive loss. Because the Company does not intend to sell any investments which have an unrealized loss position at this time, and it is not more likely than not that the Company will be required to sell the investment before recovery of its amortized cost basis, which may be maturity, the reserve for available-for-sale debt securities was zero as of September 30, 2021 and December 31, 2020.

The following table shows the fair values and the gross unrealized losses of these available-for-sale investments aggregated by investment category as of September 30, 2021.


	Adjusted Cost		Gross Unrealized Loss		Fair Value
U.S. government securities	$	16,024	$	(10)	$	16,014
Corporate bonds and commercial paper	29,927		(9)		29,918
	$	45,951	$	(19)	$	45,932

The following table shows the fair values and the gross unrealized losses of these available-for-sale investments aggregated by investment category as of December 31, 2020:


	Adjusted Cost		Gross Unrealized Loss		Fair Value
U.S. government securities	$	90,120	$	(14)	$	90,106
Corporate bonds and commercial paper	21,445		(9)		21,436
	$	111,565	$	(23)	$	111,542