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

The Company invests in a variety of financial instruments and, by its policy, limits the amount of credit exposure with any one issuer, industry or geographic area.

Accounts receivable are typically unsecured and are concentrated in the pharmaceutical industry and government sector. Accordingly, the Company may be exposed to credit risk generally associated with pharmaceutical companies and government funded entities. The Company has not historically experienced any significant losses due to concentration of credit risk.

	September 30,		December 31,
	2020		2019
U.S. Food and Drug Administration	$	44	$	176
Vifor (International) Ltd., and/or its affiliates, or collectively, Vifor		58		—
	$	102	$	176

Basic net loss per common share is computed by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents.

Diluted net loss per share is computed by dividing net loss attributable to common stockholders by the sum of the weighted-average number of common shares outstanding and dilutive common stock equivalent shares outstanding for the period. The Company’s potentially dilutive common stock equivalent shares, which include incremental common shares issuable upon (i) the exercise of outstanding stock options and warrants, (ii) vesting of restricted stock units (RSUs) and restricted stock awards (RSAs), and (iii) the purchase from contributions to the 2012 Employee Stock Purchase Plan (the ESPP) (calculated based on the treasury stock method), are only included in the calculation of diluted net loss per share when their effect is dilutive.

For the three and nine months ended September 31, 2020 and 2019, the following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect (in thousands):

	Three and Nine Months Ended September 30,
	2020		2019
Options to purchase common stock, including purchases from contributions to ESPP		7,416		11,059
Restricted stock units		389		402
Restricted stock awards		14		41
Warrants to purchase common stock		150		150
		7,969		11,652

Comprehensive loss comprises net loss and other comprehensive gain (loss). For the periods presented, other comprehensive gain (loss) consists of unrealized gains (losses) on the Company’s available-for-sale securities. For the three and nine months ended September 30, 2020, there were no significant sales of investments and therefore there were no reclassifications of comprehensive loss. For the three and nine months ended September 30, 2019, amounts reclassified from accumulated other comprehensive income to net loss for unrealized gains (losses) on available-for-sale securities were not significant, and were recorded as part of other income, net in the Condensed Consolidated Statements of Operations.

In June 2016, the Financial Accounting Standard Board issued ASU 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments. The new standard replaces the incurred loss impairment methodology under the current standard with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The Company is required to use a forward-looking expected credit loss model for accounts receivable and other financial instruments. Credit losses relating to available-for-sale debt securities will also be recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. The new standard became effective for the Company on January 1, 2020. The Company’s adoption on January 1, 2020 did not have a material impact on the consolidated financial statements.

The Company has reviewed other recent accounting pronouncements and concluded they are either not applicable to the business or that no material effect is expected on the consolidated financial statements as a result of future adoption.