Shareholders' Equity | 7. Shareholders’ Equity Equity Compensation Plans We have a stock plan (the “Stock Plan”) and an inducement stock plan for newly hired employees (together with the Stock Plan, the “Plans”). Under the Plans, stock options to purchase shares of our common stock may be granted with a fixed exercise price that is equal to the fair market value of our common stock on the date of grant. These options have a term of up to 10 Stock-Based Compensation The estimated fair value of stock-based awards is recognized as compensation expense over the vesting period of the award, net of estimated forfeitures. We estimate forfeitures based on historical experience and expected future activities. The fair value of RSUs is determined based on the number of shares granted and the quoted price of our common stock on the date of grant. The fair value of stock option awards is estimated at the grant date based on the fair value of each vesting tranche as calculated by the Black-Scholes-Merton (“BSM”) option-pricing model. The BSM model requires various highly judgmental assumptions including expected volatility and option life. If any of the assumptions used in the BSM model change significantly, stock-based compensation expense may differ materially in the future from that recorded in the current period. The fair values of our stock option grants were estimated with the following weighted average assumptions Three Months Ended March 31, 2020 2019 Dividend yield 0 % 0 % Expected life 4.9 years 6.0 years Expected volatility 60 % 64 % Risk-free interest rate 1.1 % 2.2 % The impact on our results of operations from stock-based compensation expense was as follows (in thousands, except per share amounts Three Months Ended March 31, 2020 2019 Cost of revenue — Edge to Cloud $ 4 $ 6 Selling, general and administrative 206 188 Research and development 5 (26 ) Total stock-based compensation expense $ 215 $ 168 Stock Option Activity The following table summarizes stock option activity under the Plans Weighted Average Remaining Number of Weighted Average Contractual Life Aggregate Shares Exercise Price (in years) Intrinsic Value Balance at December 31, 2019 1,544,826 $ 2.74 7.47 $ 46,582 Granted 564,900 1.02 Exercised — — Forfeited (1,500 ) 4.02 Expired (168,448 ) 4.79 Balance at March 31, 2020 1,939,778 2.06 8.62 — Vested and expected to vest at March 31, 2020 1,631,708 2.19 8.46 — Exercisable at March 31, 2020 467,687 $ 3.88 6.14 $ — At March 31, 2020, total compensation cost related to stock options granted but not yet recognized, net of estimated forfeitures, Three Months Ended March 31, 2020 2019 Weighted average grant-date fair value of options granted during the period $ 1.02 $ 1.97 Options in-the-money (in shares) — 6,000 Aggregate intrinsic value of options exercised during the period $ — $ — The aggregate intrinsic value represents the difference between the exercise price of the underlying options and the quoted price of our common stock for the number of options exercised during the period. We issue new shares of common stock upon exercise of stock options. Restricted Stock Unit Activity The following table Number of Weighted Average Shares Award Price Unvested at December 31, 2019 112,846 $ 1.44 Granted — — Vested (56,425 ) 1.44 Forfeited — — Unvested at March 31, 2020 56,421 $ 1.44 Expected to vest after March 31, 2020 159,795 $ 1.44 At March 31, 2020, total compensation cost related to RSUs granted but not yet recognized, net of estimated forfeitures, Common Stock Reserved for Future Issuance The following table March 31, 2020 Stock options outstanding 1,939,778 Restricted stock units outstanding 56,421 Stock options and restricted stock units available for future grant 1,335,084 Common stock reserved for future issuance 3,331,283 |