In May, June and July 2018, the Company raised an aggregate total of $85.4 million in funding through the sale and issuance of 319,305,718 shares of Series E redeemable convertible preferred stock at $0.2674 per share.

Redeemable convertible preferred stock, $0.001 par value, as of December 31, 2017 consisted of:

	Shares Authorized		Shares Issued and Outstanding		Original Issue Price Per Share		Carrying Value		Liquidation Preference
	(in thousands, except for share and per share amounts)
Series A		3,503,692		3,503,692	$	0.5900	$	1,992	$	2,067
Series B		24,515,966		24,345,936		0.8822		19,865		21,478
Series C		78,582,049		76,102,337		0.4797		38,035		36,506
Series C-2		8,338,892		8,338,892		0.5996		4,845		5,000
Series D		43,362,233		43,362,233		0.5996		25,900		26,000
Series D-2		18,779,561		18,097,331		0.6596		11,868		11,937
Balance at December 31, 2017		177,082,393		173,750,421			$	102,505	$	102,988

In connection with the completion of the Company’s IPO in October 2018, all outstanding shares of Series A, Series B, Series C, Series C-2, Series D, Series D-2 and Series E were converted into 16,028,462 shares of common stock. As such, no redeemable convertible preferred stock shares were outstanding as of December 31, 2018.

During the period from 2008 to 2012, the Company issued various warrants for the purchase of redeemable convertible preferred stock in connection with debt financings and the issuance of redeemable convertible preferred stock.

In August 2017, the Company issued warrants to Oxford and SVB to purchase an aggregate of 682,230 shares of Series D-2 redeemable convertible preferred stock at an exercise price of $0.6596 per share in connection with the issuance of August 2017 Loan (see Note 7). If there was a subsequent convertible preferred stock or other senior equity securities financing with a per share price less than the Series D-2 redeemable convertible preferred per share price, then the warrant would automatically convert to a warrant to purchase such class of shares, based on the per share price of such equity. Given that the price per share of the Series E redeemable convertible preferred stock described above was less than the price per share of the Series D-2 redeemable convertible preferred stock, the 2017 Warrant converted into a warrant to purchase a total of 1,682,871 shares of Series E redeemable convertible preferred stock at an exercise price of $0.2674 per share. The warrant is exercisable from the original date of issuance and has a 10-year term.

The Company adjusted the warrant liability for changes in fair value until the completion of its IPO on October 1, 2018, at which time certain convertible preferred stock warrants were converted into warrants for the purchase of common stock and the related convertible preferred stock warrant liability was reclassified to additional paid-in capital and others expired. On October 1, 2018, 1,232,220 shares of the Series C redeemable convertible preferred warrants were canceled, and the remaining 687,928 shares were converted to warrants to purchase common stock on a 1-for-0.0370 basis. All Series E redeemable convertible preferred warrants were converted to warrants to purchase common stock on a 1-for-0.0275 basis.

As of December 31, 2018 and 2017, the warrants related to redeemable convertible preferred stock outstanding and exercisable and their estimated fair value were as follows:

		Exercise Price Per Share		Shares as of December 31,				Estimated Fair Value as of December 31,
Stock	Expiration Date	2018		2018		2017		2018		2017
	(in thousands except for share and per share amounts)
Series B redeemable convertible preferred	June 2018	$	-		-		170,030	$	-	$	116
Series C redeemable convertible preferred	September 2018		-		-		2,479,712		-		1,263
Series D-2 redeemable convertible preferred	September 2018		-		-		682,230		-		329
Series E redeemable convertible preferred	September 2018		-				-		-		-
Total					-		3,331,972	$	-	$	1,708

Upon the completion of IPO on October 1, 2018, a majority of the redeemable convertible preferred stock warrants were converted into 71,813 shares of common stock warrants and were no longer revalued to fair value. As of September 30, 2018 and years ended December 31, 2017 and 2016, the warrants were valued using the Option Pricing Method and were estimated using the following assumptions:

	Nine months Ended		Year Ended December 31,
	September 30, 2018		2017			2016
Average expected life (in years)	3.1-8.8			2.5			2.5
Expected volatility	62.42%-71.21%			85.3	%		84.7	%
Risk-free interest rate	2.88%-3.40%			1.55	%		0.83	%
Expected dividend		-		-			-

Holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders of the Company.

As of December 31, 2018, the Company had reserved common stock, on an if-converted basis, for issuance as follows:

	December 31,
	2018		2017
Redeemable convertible preferred stock		-		5,063,404
Common stock options issued and outstanding		3,111,718		835,320
Common stock award issued and outstanding		311,240		-
Remaining shares reserved for issuance under 2004 and 2018 Equity Incentive Plan		2,525,610		91,149
Shares reserved for issuance under 2018 Employee Stock Purchase Plan		230,000		-
Warrants to purchase redeemable convertible preferred stock		-		93,527
Warrant to purchase common stock		71,813		1,099
Total		6,250,381		6,084,499

Effective October 30, 2018, the Company had 10,000,000 shares of preferred stock authorized with a par value of $0.001. No shares of preferred stock were outstanding as of December 31, 2018.