Note 9. Stockholders’ Equity

Underwritten Public Offering of Common Stock 

During the quarter ended December 31, 2018, the Company sold a total of 7,250,000 shares of its common stock at a price to the public of $4.25 per share for aggregate gross proceeds of $30.8 million before deducting the underwriting discount and offering expenses payable by the Company of approximately $2.1 million. The Company expects to use the proceeds of the offering to fund the Company’s operations and growth of its business, including for capital expenditures, working capital, research and development, the commercialization of its technology and other general corporate purposes.

During the quarter ended December 31, 2018, the Company also issued 112,365 shares of its common stock to investors in the Company’s private placement that closed in May 2017. These issuances were made pursuant to the price-protection provisions granted to such investors in their subscription agreements. 

Equity incentive plans

During the six months ended December 31, 2018, the Company granted employees and directors options to purchase an aggregate of 836,955 shares of common stock with a weighted average grant date fair value of $2.68. The fair values of the Company’s options were estimated at the dates of grant using a Black-Scholes option pricing model with the following weighted average assumptions:

Expected term: The Company’s expected term is based on the period the options are expected to remain outstanding. The Company estimated this amount utilizing the “Simplified Method” in that the Company does not have sufficient historical experience to provide a reasonable basis to estimate an expected term.

Risk-free interest rate: The Company uses the risk-free interest rate of a U.S. Treasury Note with a similar term on the date of the grant.

Volatility: The Company calculates the expected volatility of the stock price using the historical volatilities of the Company’s common stock traded on the Nasdaq Capital Market.

Dividend yield: The Company uses a 0% expected dividend yield as the Company has not paid dividends to date and does not anticipate declaring dividends in the near future. 

During the six months ended December 31, 2018 the Company awarded certain employees and contractors grants of an aggregate of 494,880 restricted stock units (“RSUs”) with a weighted average grant date fair value of $5.95. The RSUs will be expensed over the requisite service period. The terms of the RSUs include vesting provisions based solely on continued service. If the service criteria are satisfied, the RSUs will generally vest over 4 years.

During the six months ended December 31, 2018 the Company granted 119,500 performance-based restricted stock units (“PBRSU”) to employees with a weighted average grant date fair value per share of $8.30. The PBRSU awards contain performance and service conditions which must be satisfied for an employee to earn the award.

Any portion of grants awarded to consultants and other service providers as to which the repurchase option for restricted stock awards has not lapsed or for which an option or restricted stock unit has not vested is accrued on the Condensed Consolidated Balance Sheet as a component of accounts payable and accrued expenses. As of December 31, 2018, and June 30, 2018, the accrued stock-based compensation was $142,144 and $395,539, respectively.

Compensation expense related to our stock-based awards described above was as follows:

Unrecognized stock-based compensation expense and weighted-average years to be recognized are as follows: