The Company issued warrants to purchase shares of convertible preferred stock in conjunction with the sale of certain of the convertible preferred shares and issuance of debt. The estimated grant date fair value as well as the estimated fair value at each reporting date of the warrants was determined using the Black‑Scholes option pricing model with weighted average assumptions substantially consistent with those disclosed for stock options (see Note 14 – Shared Based Compensation), other than term, which is the contractual term of the warrant and the use of the exercise price and estimated fair value of the underlying series of convertible preferred stock. At December 31, 2019 and through the closing of the Company’s initial public offering, the preferred warrants were classified as liabilities with estimated fair value remeasured at each reporting date reported within in the accompanying statements of operations.

The following table presents the activity for convertible preferred stock warrants (in thousands, except weighted average exercise price):

	Series E						Series G
	Warrants			Weighted Average Exercise price			Warrants			Weighted Average Exercise price
Outstanding ‑ December 31, 2019		925		$	5.00			613		$	0.75
Granted		—			—			—			—
Forfeited/canceled		(925	)		(5.00	)		—			—
Exercised		—			—			—			—
Reclassification of warrant liability to additional paid-in capital		—			—			(613	)		(0.75	)
Outstanding ‑ December 31, 2020		—		$	—		$	—		$	—

Upon closing of the Company’s initial public offering, the then outstanding Series G convertible preferred stock was automatically converted to common stock and the outstanding warrants to purchase Series G convertible preferred stock were automatically converted to warrants to purchase 103,326 shares of common stock at $4.46 per share and expire in February 2028. The warrants were remeasured to an estimate of fair value as of the initial public offering with the change in fair value of $1.3 million recognized in our statements of operations. The carrying value of the warrants was reclassified to additional paid-in capital as a result of the initial public offering.