Stock-Based Compensation	6 Months Ended
Jun. 30, 2019
Stock-Based Compensation [Abstract]
Stock-Based Compensation	Note 5 — Stock-Based Compensation We have a stock incentive plan for employees and others called the VirnetX Holding Corporation 2013 Equity Incentive Plan (the “Plan”), which has been approved by our stockholders. In April 2017, the Board approved an amendment and restatement of the Plan to, among other things, increase the shares reserved under the Plan by 2,500,000 shares (the “Plan Amendment”). Our stockholders approved of the Plan Amendment at the 2017 Annual Meeting of Stockholders held on June 1, 2017. The Plan provides for grants of 16,624,469 shares of our common stock, including stock options and restricted stock units (“RSUs”), and will expire in 2023. As of June 30, 2019, 1,128,903 shares remained available for grant under the Plan. During the three months ended June 30, 2019, we granted options for a total of 345,000 shares with a weighted average grant date fair value of $4.63 per option. During the three months ended June 30, 2018, we granted options totaling 340,000 shares with a weighted average grant date fair value of $2.31. During the six months ended June 30, 2019, we granted options for a total of 345,000 shares. The weighted average fair value at the grant dates for options issued during the six months ended June 30, 2019 was $4.63 per option. The fair values of options at the grant date were estimated utilizing the Black-Scholes valuation model with the following weighted average assumptions for the six months ended June 30, 2019 (i) dividend yield on our common stock of 0 percent (ii) expected stock price volatility of 92 percent (iii) a risk-free interest rate of 2.09 percent and (iv) and expected option term of 6 years. During the six months ended June 30, 2018, we granted options for a total of 1,010,000 shares with a weighted average grant date fair value of $2.52. The fair values of options at the grant date were estimated utilizing the Black-Scholes valuation model with the following weighted average assumptions for the six months ended June 30, 2018 (i) dividend yield on our common stock of 0 percent (ii) expected stock price volatility of 85 percent (iii) a risk-free interest rate average of 2.65 percent and (iv) an expected option term of 6 years. During the three months ended June 30, 2019 and 2018, we granted 229,996 and 226,663 RSUs, respectively. The weighted average fair values at the grant dates for RSUs issued during the three months ended June 30, 2019 and 2018 were $6.06 and $3.19 per RSU, respectively. RSUs, which are subject to forfeiture if service terminates prior to the shares vesting, are expensed ratably over the vesting period. During the three months ended June 30, 2019 and 2018, we paid $47 and $33 in withholding taxes on shares issued upon conversion of RSUs. The underlying shares were canceled. These amounts are reflected as financing costs in the accompanying statement of cash flows. During the six months ended June 30, 2019 and 2018, we granted 229,996 and 246,663 RSUs, respectively. The weighted average fair values at the grant dates for RSUs issued during the six months ended June 30, 2019 and 2018 were $6.06 and $3.28 per RSU, respectively. RSUs, which are subject to forfeiture if service terminates prior to the shares vesting, are expensed ratably over the vesting period. During the six months ended June 30, 2019 and 2018, we paid $47 and $33 in withholding taxes on shares issued upon conversion of RSUs. The underlying shares were canceled. These amounts are reflected as financing costs in the accompanying statement of cash flows. Stock-based compensation expense included in general and administrative expense was $498 and $872 and in research and development expense was $430 and $841 for the three and six months ended June 30, 2019, respectively, and $467 and $855 for general and administrative expense and $655 and $1,154 for research and development expense for the three and six months ended June 30, 2018, respectively. As of June 30, 2019, the unrecognized stock-based compensation expense related to non-vested stock options and RSUs was $6,284 and $2,396, respectively, which will be amortized over an estimated weighted average period of approximately 2.50 and 2.84 years, respectively. During the six-month period ended June 30, 2019 we issued 663,816 new shares of common stock as a result of the exercise of options and 182,618 shares of common stock as a result of vesting RSUs.

Note 5 — Stock-Based Compensation

We have a stock incentive plan for employees and others called the VirnetX Holding Corporation 2013 Equity Incentive Plan (the “Plan”), which has been approved by our stockholders. In April 2017, the Board approved an amendment and restatement of the Plan to, among other things, increase the shares reserved under the Plan by 2,500,000 shares (the “Plan Amendment”). Our stockholders approved of the Plan Amendment at the 2017 Annual Meeting of Stockholders held on June 1, 2017. The Plan provides for grants of 16,624,469 shares of our common stock, including stock options and restricted stock units (“RSUs”), and will expire in 2023. As of June 30, 2019, 1,128,903 shares remained available for grant under the Plan.

During the three months ended June 30, 2019, we granted options for a total of 345,000 shares with a weighted average grant date fair value of $4.63 per option. During the three months ended June 30, 2018, we granted options totaling 340,000 shares with a weighted average grant date fair value of $2.31.

During the six months ended June 30, 2019, we granted options for a total of 345,000 shares. The weighted average fair value at the grant dates for options issued during the six months ended June 30, 2019 was $4.63 per option. The fair values of options at the grant date were estimated utilizing the Black-Scholes valuation model with the following weighted average assumptions for the six months ended June 30, 2019 (i) dividend yield on our common stock of 0 percent (ii) expected stock price volatility of 92 percent (iii) a risk-free interest rate of 2.09 percent and (iv) and expected option term of 6 years.

During the six months ended June 30, 2018, we granted options for a total of 1,010,000 shares with a weighted average grant date fair value of $2.52. The fair values of options at the grant date were estimated utilizing the Black-Scholes valuation model with the following weighted average assumptions for the six months ended June 30, 2018 (i) dividend yield on our common stock of 0 percent (ii) expected stock price volatility of 85 percent (iii) a risk-free interest rate average of 2.65 percent and (iv) an expected option term of 6 years.

During the three months ended June 30, 2019 and 2018, we granted 229,996 and 226,663 RSUs, respectively. The weighted average fair values at the grant dates for RSUs issued during the three months ended June 30, 2019 and 2018 were $6.06 and $3.19 per RSU, respectively. RSUs, which are subject to forfeiture if service terminates prior to the shares vesting, are expensed ratably over the vesting period. During the three months ended June 30, 2019 and 2018, we paid $47 and $33 in withholding taxes on shares issued upon conversion of RSUs. The underlying shares were canceled. These amounts are reflected as financing costs in the accompanying statement of cash flows.

During the six months ended June 30, 2019 and 2018, we granted 229,996 and 246,663 RSUs, respectively. The weighted average fair values at the grant dates for RSUs issued during the six months ended June 30, 2019 and 2018 were $6.06 and $3.28 per RSU, respectively. RSUs, which are subject to forfeiture if service terminates prior to the shares vesting, are expensed ratably over the vesting period. During the six months ended June 30, 2019 and 2018, we paid $47 and $33 in withholding taxes on shares issued upon conversion of RSUs. The underlying shares were canceled. These amounts are reflected as financing costs in the accompanying statement of cash flows.

Stock-based compensation expense included in general and administrative expense was $498 and $872 and in research and development expense was $430 and $841 for the three and six months ended June 30, 2019, respectively, and $467 and $855 for general and administrative expense and $655 and $1,154 for research and development expense for the three and six months ended June 30, 2018, respectively.

As of June 30, 2019, the unrecognized stock-based compensation expense related to non-vested stock options and RSUs was $6,284 and $2,396, respectively, which will be amortized over an estimated weighted average period of approximately 2.50 and 2.84 years, respectively.

During the six-month period ended June 30, 2019 we issued 663,816 new shares of common stock as a result of the exercise of options and 182,618 shares of common stock as a result of vesting RSUs.