During the three and six months ended December, 31, 2019, the Company granted an aggregate of 1,192,000 shares and 2,738,740 shares of stock options, respectively, with weighted average exercise prices of $17.37 and $15.12 per share, respectively. The fair value of options granted before the closing of the IPO was estimated at the date of grant using the Black-Scholes option-pricing model with the following assumptions: (i) expected term of 6.25 years, (ii) expected volatility of 50%, (iii) risk-free interest rate range of 1.59% to 1.88% and (iv) expected dividend yield of 0%.

As of December 31, 2019, there was $29.8 million of unamortized stock-based compensation cost related to unvested stock options, which the Company expects to recognize over a weighted-average period of 3.25 years.

On November 26, 2019, the Company’s board of directors approved the 2019 Employee Stock Purchase Plan (ESPP), which became effective on December 11, 2019, the date the Company’s Registration Statement on Form S-1 was declared effective by the SEC. The ESPP is intended to qualify under Section 423 of the Internal Revenue Code of 1986 (as amended) and will provide eligible employees a means to acquire shares of common stock through payroll deductions. Under the ESPP, the Company initially reserved for issuance 1,400,000 shares of common stock, which will increase automatically on July 1 of each fiscal year during the term of the ESPP by the number of shares equal to 1% of the total number of shares of common stock and preferred stock (on as-converted basis) outstanding as of the immediately preceding June 30th, unless the board of directors elects to authorize a lesser number of shares; provided, that, the total number of shares issued under the ESPP may not exceed 14,000,000 shares of common stock.

The ESPP provides for consecutive offering periods during which eligible employees can participate in the ESPP and be granted the right to purchase shares. The first business day of each offering period is the offering date. No offering period may last more than 27 months. Each offering period will be comprised of two six-month purchase periods. The initial offering period of the ESPP started on December 11, 2019, which is the effective date of the ESPP, and will end on February 14, 2021, with two purchase periods on August 14, 2020 and February 14, 2021. All eligible employees were automatically enrolled in the ESPP for the initial offering period, unless an employee withdraws from the ESPP on or before January 15, 2020. Thereafter, a new 12-month offering period will commence on each subsequent February 15^th and August 15th (or if such date is not a business day, then on the business day immediately following such date), with each such offering period consisting of two separate 6-month purchase periods ending on August 14^th and February 14^th, respectively. Eligible employees can contribute up to 15% of their eligible compensation, subject to limitation as provided for in the ESPP, and purchase the common stock at a purchase price per share equal to 85% of the lesser of the fair market value of the common stock on (i) the offering date or (ii) the purchase date.

Stock-based compensation expense was included in the following line items in the accompanying condensed consolidated statements of operations during the periods presented (in thousands):

	Three months ended December 31,				Six months ended December 31,
	2019		2018		2019		2018
Cost of revenue	$	211	$	42	$	359	$	112
Research and development		1,084		119		1,755		352
Sales and marketing		494		122		877		288
General and administrative		1,286		311		2,360		449
	$	3,075	$	594	$	5,351	$	1,201

The Company has an agreement with a customer to issue warrants for up to 5.6 million shares of the Company’s common stock at an exercise price of $4.50 per share over a period of five years. Issuance of the warrants is contingent upon certain performance conditions and subject to certain limits. As of December 31, 2019, there were no warrants issued or issuable under this agreement. The Company has concluded that the performance conditions for the issuance of this warrant are not probable of being met.