16. Stock-based compensation

Stock options

A summary of the Company’s stock option activity and related information for the six months ended June 30, 2026 is as follows:

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The fair value of each stock option granted during the six months ended June 30, 2026 and 2025 was estimated on the grant date using the Black-Scholes option-pricing model using the following weighted-average assumptions:

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Restricted stock units

A summary of the Company’s restricted stock unit activity and related information for the six months ended June 30, 2026 is as follows:

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Employee stock purchase plan

At the Special Meeting of Stockholders, held on December 18, 2018, the stockholders approved the 2018 Employee Stock Purchase Plan (“2018 ESPP”). On June 21, 2019, the board of directors of the Company amended and restated the 2018 ESPP, to account for certain non-material changes to the plan’s administration and, effective May 30, 2023, in connection with the Reverse Stock Split, the board of directors amended and restated the 2018 ESPP to account for the adjustments to the share reserves. At the Company’s 2026 Annual General Meeting of Shareholders in May 2026, the Company’s shareholders approved the Amended and Restated 2018 ESPP (the “Amended and Restated 2018 ESPP”). The Amended and Restated 2018 ESPP provides eligible employees with the opportunity, through regular payroll deductions, to purchase shares of the Company’s common stock at 85% of the lesser of the fair market value of the

common stock on (a) the date the option is granted, which is the first day of the purchase period, and (b) the exercise date, which is the last business day of the purchase period. The Amended and Restated 2018 ESPP generally allows for two six-month purchase periods per year beginning in January and July, or such other periods as determined by the compensation committee of the Company’s board of directors. The fair value of shares expected to be purchased under the Amended and Restated 2018 ESPP was calculated using the following weighted-average assumptions:

For the six months ended June 30, 2026 and 2025, the Company recognized less than $0.1 million in each period of stock-based compensation expense under the Amended and Restated 2018 ESPP. During the six months ended June 30, 2026, the Company issued 10,240 shares of common stock for proceeds of less than $0.1 million under the Amended and Restated 2018 ESPP.