Note 15. Stockholders' Equity

​

Share Buyback Program

​

Pursuant to the Company’s existing share buyback program, the Company purchased 1,373,345 and 393,836 shares of its common stock, totaling $29.5 million and $11.0 million, for the three months ended March 31, 2026 and 2025, respectively.

​

In March 2026, the Company’s Board of Directors authorized a $50.0 million increase to the Company’s share buyback program, which is expected to continue for an indefinite period of time. Since the inception of the program, the Company’s Board of Directors have authorized a total of $485.0 million in the share buyback program. The primary goal of the program is to offset dilution created by the Company’s equity compensation programs.

​

Purchases are made through open market and private block transactions pursuant to Rule 10b5-1 plans, privately negotiated transactions or other means as determined by the Company’s management and in accordance with the requirements of the SEC and applicable laws. The timing and actual number of treasury share purchases will depend on a variety of factors including price, corporate and regulatory requirements, and other conditions. These treasury share purchases are accounted for under the cost method and are included as a component of treasury stock in the Company’s condensed consolidated balance sheets.

​

Amended and Restated 2015 Equity Incentive Plan

​

In February 2024, the Board of Directors approved the Company’s amended and restated 2015 Equity Incentive Plan, or the Amended 2015 Plan, which was subsequently approved by the Company’s stockholders, and accordingly, adopted by the Company in June 2024. The Amended 2015 Plan, among other things, extended the term of the 2015 Equity

Incentive Plan, or the Original 2015 Plan, increased the number of shares available for issuance under the Original 2015 Plan, and removed the evergreen provision. The term of the Amended 2015 Plan will be extended indefinitely, however, the Company’s ability to grant incentive stock options thereunder will continue through February 2034.

​

As of March 31, 2026, the Company reserved an aggregate of 4,707,576 shares of common stock for future issuance under the Amended 2015 Plan.

​

2014 Employee Stock Purchase Plan

​

As of March 31, 2026, the Company has issued 1,443,046 shares of common stock under the ESPP and 556,954 shares of its common stock remain available for issuance under the ESPP.

​

For the three months ended March 31, 2026 and 2025, the Company recorded ESPP expense of $0.3 million and $0.3 million, respectively.

​

Share-Based Award Activity and Balances

​

The Company accounts for share-based compensation payments in accordance with ASC 718, which requires measurement and recognition of compensation expense at fair value for all share-based payment awards made to employees and directors. Under these standards, the fair value of option awards and the option components of the ESPP awards are estimated at the grant date using the Black-Scholes option-pricing model. The fair value of RSUs is estimated at the grant date using the Company’s common share price. The Company records share-based compensation expense net of expected forfeitures. Compensation cost for all share-based payments granted with service-based graded vesting schedules is recognized using the straight-line method over the requisite service period.

​

The weighted-averages for key assumptions used in determining the fair value of options granted are as follows:

​

​

A summary of option activity under all plans for the three months ended March 31, 2026, is presented below:

​

​

For the three months ended March 31, 2026 and 2025, the Company recorded expense of $4.7 million and $4.2 million, respectively, related to stock options granted under all plans.

​

Information relating to option grants and exercises is as follows:

​

​

A summary of the status of the Company’s non-vested options as of March 31, 2026, and changes during the three months ended March 31, 2026, are presented below:

​

​

As of March 31, 2026, there was $31.1 million of total unrecognized compensation cost, net of forfeitures, related to non-vested stock option-based compensation arrangements granted under all plans. The cost is expected to be recognized over a weighted-average period of 3.1 years and will be adjusted for future changes in estimated forfeitures.

​

Restricted Stock Units

​

The Company grants restricted stock units, or RSUs, to certain employees and members of the Board of Directors with a vesting period of up to four years. The grantee receives one share of common stock at a specified future date for each RSU awarded. The RSUs may not be sold or otherwise transferred until vested. The RSUs do not have any voting or dividend rights prior to the issuance of the underlying common stock. The share-based expense associated with these grants was based on the Company’s common stock fair value at the time of grant and is amortized over the requisite service period, which generally is the vesting period using the straight-line method. For the three months ended March 31, 2026 and 2025, the Company recorded expenses of $4.3 million and $3.9 million, respectively, related to RSU awards granted under all plans.

​

As of March 31, 2026, there was $32.2 million of total unrecognized compensation cost, net of forfeitures, related to non-vested RSU based compensation arrangements granted under all plans. The cost is expected to be recognized over a weighted-average period of 3.0 years and will be adjusted for future changes in estimated forfeitures.

​

Information relating to RSU grants and deliveries is as follows:

​

​

Share-based Compensation Expense

​

The Company recorded share-based compensation expense, which is included in the Company’s condensed consolidated statement of operations as follows:

​

​