12. Stockholders’ equity

Shares issued

During the nine months ended September 30, 2023, the Company issued 1,413,886 shares of common stock upon vesting of Restricted Stock Units ("RSUs") granted by the Company to management and employees, including 510,632 of reissued treasury stock. We withheld 939,198 shares to satisfy approximately $1,091,000 of employees’ tax obligations during the nine months ended September 30, 2023. We treat shares of common stock withheld for tax purposes on behalf of our employees in connection with the vesting of RSUs in a similar manner as common stock repurchases and reported as treasury stock. 

During the nine months ended September 30, 2023, the Company issued 130,918 shares of common stock upon vesting of RSUs granted to Board members.

During the nine months ended September 30, 2023, the Company issued 3,244,302 shares of common stock pursuant to the At The Market Issuance Sales Agreement for net proceeds of $3.8 million.

During the nine months ended September 30, 2023, the Company issued 15,781 shares of common stock to a former Board member to fulfill obligations related to consulting services.

During the nine months ended September 30, 2023, the Company issued 84,619 shares of common stock to a Board member related to director fees.

During the nine months ended September 30, 2023, the Company issued 469,366 shares of common stock upon the settlement of the securities class action lawsuit.

During the nine months ended September 30, 2023, the Company issued 192,707 shares of common stock pursuant to the employee stock purchase plan.

In July 2023, the Company completed a public offering of 18,193,000 shares of its common stock, for net proceeds of $18.3 million.

In August 2023, the Company issued 4,545,455 shares of its common stock pursuant to that certain Securities Purchase Agreement (the “Yulho SPA”), with Yulho Co, Ltd., for net proceeds of $4.6 million.

Warrant issued

In July 2023, the Company issued a warrant to purchase 363,860 shares of the Company's common stock to the underwriter of the Company's public offering, equal to 2% of the 18,193,000 shares sold. The warrants are exercisable at $1.375 per share, commencing six months after July 17, 2023. The warrants have an expiration date of 5 years from the date of issuance and will expire on  July 17, 2028.

In August 2023, the Company issued a warrant to purchase 205,761 shares of the Company's common stock to the underwriter of the transaction in connection with the Yulho SPA. The warrants have an expiration date of 5 years from the date of issuance and are exercisable immediately at $1.25 per share. The warrant will expire on August 4, 2028.

Stock-based compensation

The stock-based compensation expense was allocated as follows:

There were no options issued during the three and nine months ended September 30, 2023 or the three and nine months ended September 30, 2022.

2014 Stock Incentive Plan

We have adopted the Aqua Metals, Inc. 2014 Stock Incentive Plan providing for the grant of non-qualified stock options and incentive stock options to purchase shares of our common stock and for the grant of restricted and unrestricted share grants. All of our officers, directors, employees and consultants are eligible to participate under the plan. The purpose of the plan is to provide eligible participants with an opportunity to acquire an ownership interest in our company. As of  September 30, 2023, there were 522,020 remaining shares available for future grants.

2019 Stock Incentive Plan

In 2019, our board of directors adopted the Aqua Metals, Inc. 2019 Stock Incentive Plan (the “2019 Plan”). A total of 18,500,000 shares of common stock was authorized for issuance pursuant to the 2019 Plan. The 2019 Plan provides for the following types of stock-based awards: incentive stock options; non-statutory stock options; restricted stock; and performance stock. The 2019 Plan, under which equity incentives may be granted to employees and directors under incentive and non-statutory agreements, requires that the option price may not be less than the fair value of the stock at the date the option is granted. Option awards are exercisable until their expiration, which may not exceed 10 years from the grant date. As of  September 30, 2023, there were 5,385,633 remaining shares available for future grants.

(1) Consists of 840,000 shares relating to outstanding options granted in reliance on Nasdaq Rule 5635(c)(4).

Restricted stock units

During the first quarter of 2023, the Company granted 64,149 RSUs, all of which were subject to vesting, with a grant date fair value of $70,000 to employees. The shares vest in three equal installments over a three-year period.

During the second quarter of 2023, the Company granted 204,547 RSUs, all of which were subject to vesting, with a grant date fair value of $225,000 to Board Members. The shares vest in four equal installments over a twelve-month period.

During the third quarter of 2023, the Company granted 136,254 RSUs, all of which were subject to vesting, with a grant date fair value of $155,000 to employees. The shares vest in three equal installments over a three-year period.