In May 2021, our stockholders approved an amendment to our Restated Certificate of Incorporation to increase the total number of authorized shares of common stock from 450,000,000 to 675,000,000 shares.

On May 27, 2020, we completed an underwritten public offering of 107,049,375 shares of our common stock and a pre-funded warrant to purchase 8,335,239 shares of our common stock, together with accompanying stock purchase warrants to purchase 57,692,307 shares of our common stock. The shares of common stock and the pre-funded warrant were immediately separable from the stock purchase warrants. All of the securities were issued separately. The combined public offering price of the common stock and accompanying stock purchase warrants was $1.30 per share. The stock purchase warrants have an exercise price of $1.30 per share and are exercisable immediately. The term of the stock purchase warrants expires on the earlier to occur of (a) the date that is 30 business days following the date on which we first issue a press release disclosing, if applicable, positive top-line safety and efficacy results from IMerge Phase 3 and (b) December 31, 2025. The combined public offering price of the pre-funded warrant and accompanying stock purchase warrants was $1.299 per share. The pre-funded warrant has an exercise price of $0.001 per share and may be exercised at any time until the pre-funded warrant is exercised in full. The net cash proceeds from this offering were approximately $140,184,000, after deducting the underwriting discount and other offering expenses paid by us, and excluding any future proceeds from the exercise of the pre-funded warrant or the stock purchase warrants.

Upon the issuance of the pre-funded warrant and stock purchase warrants, we evaluated the terms of each warrant to determine the appropriate accounting and classification pursuant to FASB Accounting Standards Codification Topic 480, Distinguishing Liabilities from Equity, and FASB Accounting Standards Codification Topic 815, Derivatives and Hedging. Warrants are classified as liabilities when the warrant terms allow settlement of the warrant exercise in cash and classified as equity when the warrant terms only allow settlement in shares of common stock. The terms of the pre-funded warrant and the stock purchase warrants include certain provisions related to fundamental transactions and a cashless exercise provision in the event registered shares are not available, and do not include any mandatory redemption provisions. Based on our evaluation, we concluded the pre-funded warrant and the stock purchase warrants should be classified as equity with no subsequent remeasurement as long as such warrants continue to be classified as equity. In 2021 and 2020, stock purchase warrants for 1,906,341 and 12,500 shares of our common stock were exercised, respectively, and we received proceeds of $2,479,000 and $16,000, respectively. As of December 31, 2021, the pre-funded warrant to purchase 8,335,239 shares of our common stock was outstanding and stock purchase warrants to purchase 55,773,466 shares of our common stock were outstanding.

On May 18, 2018, we entered into an At Market Issuance Sales Agreement, or the 2018 Sales Agreement, with B. Riley FBR, Inc., or B. Riley FBR, pursuant to which we could elect to issue and sell shares of our common stock having an aggregate offering price of up to $100,000,000 in such quantities and on such minimum price terms as we set from time to time through B. Riley FBR as our sales agent. We paid B. Riley FBR an aggregate commission rate

equal to up to 3.0% of the gross proceeds of the sales price per share for common stock sold through B. Riley FBR under the 2018 Sales Agreement. From January 2020 through April 2020, we sold an aggregate of 3,496,616 shares of our common stock pursuant to the 2018 Sales Agreement, resulting in net cash proceeds to us of approximately $4,075,000, after deducting sales commissions and other offering expenses paid by us. The 2018 Sales Agreement has been superseded by the 2020 Sales Agreement (see below).

On September 4, 2020, we entered into an At Market Issuance Sales Agreement, or the 2020 Sales Agreement, with B. Riley Securities, Inc., or B. Riley Securities, pursuant to which we may elect to issue and sell shares of our common stock having an aggregate offering price of up to $100,000,000 in such quantities and on such minimum price terms as we set from time to time through B. Riley Securities as our sales agent. We agreed to pay B. Riley Securities an aggregate commission rate equal to up to 3.0% of the gross proceeds of the sales price per share for common stock sold through B. Riley Securities under the 2020 Sales Agreement. In connection with the 2020 Sales Agreement, we terminated the 2018 Sales Agreement. For the year ended December 31, 2021, we sold an aggregate of 10,571,556 shares of our common stock pursuant to the 2020 Sales Agreement, resulting in net cash proceeds to us of approximately $20,385,000, after deducting sales commissions and other offering expenses payable by us. The 2020 Sales Agreement will expire upon the earlier of: (a) the sale of all common stock subject to the 2020 Sales Agreement, or (b) September 4, 2023.

In May 2011, our stockholders approved the adoption of the 2011 Incentive Award Plan, or 2011 Plan. The 2011 Plan provided for grants of either incentive stock options or nonstatutory stock options and stock purchase rights to employees (including officers and employee directors) and consultants (including non‑employee directors). Upon the adoption of the 2018 Equity Incentive Plan in May 2018 (see below), no further grants of stock options or stock purchase rights were made from the 2011 Plan. Stock options granted under the 2011 Plan expire no later than ten years from the date of grant. Stock option exercise prices were equal to the fair market value of the underlying common stock on the date of grant.

Service‑based stock options under the 2011 Plan generally vested over a period of four years from the date of the stock option grant. Other stock awards (restricted stock awards and restricted stock units) had variable vesting schedules which were determined by our board of directors on the date of grant. All outstanding awards granted under the 2011 Plan remain subject to the terms of the 2011 Plan and the individual award agreements thereunder.

On May 15, 2018, our stockholders approved the adoption of the 2018 Equity Incentive Plan, or 2018 Plan, as the successor to the 2011 Plan. The 2018 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, other stock awards, and performance awards that may be settled in cash, stock, or other property. Eligible participants under the 2018 Plan include our employees, consultants and non-employee directors. The number of shares reserved for issuance under the 2018 Plan (subject to adjustment for certain changes in capitalization) is equal to the sum of (i) the unallocated shares of common stock remaining available for grant under the 2011 Plan as of May 15, 2018, (ii) 10,000,000 newly reserved shares of common stock and (iii) the number of shares subject to awards granted under the 2002 Equity Incentive Plan, and the 2011 Plan as such shares become available from time to time, referred to as the Prior Plans’ Returning Shares. Such Prior Plans’ Returning Shares become available for issuance under the 2018 Plan if outstanding stock awards granted under the 2002 Equity Incentive Plan and the 2011 Plan, after May 15, 2018, expire or terminate for any reason prior to exercise or settlement or are forfeited, cancelled or otherwise returned to us because of the failure to meet a contingency or condition required for the vesting of such shares, or, subject to certain exceptions, are reacquired or withheld (or not issued) by us to satisfy a tax withholding obligation in connection with a stock award. In May 2021 and June 2020, our stockholders approved amendments to our 2018 Equity Incentive Plan to increase the total number of shares issuable under such plan by 12,500,000 and 5,700,000 shares of our common stock, respectively.

Stock options granted under the 2018 Plan expire no later than ten years from the date of grant. Stock option exercise prices shall be equal to the fair market value of the underlying common stock on the date of grant. If, at the time we grant a stock option, the optionee directly or by attribution owns stock possessing more than 10% of the total combined voting power of all classes of our stock, the stock option exercise price shall be at least 110% of the fair market value of the underlying common stock and shall not be exercisable more than five years after the date of grant.

We grant service-based and performance-based stock options to employees under the 2018 Plan. Service-based stock options generally vest over a period of four years from the date of the stock option grant. Performance-based stock options vest upon the achievement of specified milestones. Other stock awards (restricted stock awards and restricted stock units) have variable vesting schedules as determined by our board of directors on the date of grant.

Under certain circumstances, stock options may be exercised prior to vesting, subject to our right to repurchase the shares underlying such stock option at the exercise price paid per share. Our repurchase rights would generally terminate on a vesting schedule identical to the vesting schedule of the exercised stock option. During 2021 and 2020, we did not repurchase any shares under the 2018 Plan. As of December 31, 2021, we have no shares outstanding subject to repurchase under the 2018 Plan.

As of December 31, 2021, our Non‑Employee Director Compensation Policy adopted by our board of directors in March 2014 and amended and restated in February 2020 provides for the automatic grant to non‑employee directors of the following types of equity awards under the 2018 Plan:

First Director Option. Each person who becomes a non‑employee director, whether by election by our stockholders or by appointment by our board of directors to fill a vacancy, will automatically be granted a stock option to purchase 120,000 shares of common stock, or First Director Option, on the date such person first becomes a non‑employee director. The First Director Option vests annually over three years upon each anniversary date of appointment to our board of directors.

Subsequent Director Option. Each non‑employee director (other than any director receiving a First Director Option on the date of the annual meeting) will automatically be granted a subsequent stock option to purchase 83,000 shares of common stock, a Subsequent Director Option, on the date of the annual meeting of stockholders in each year during such director’s service on our board of directors. The Subsequent Director Option vests in full on the earlier of: (i) the date of the next annual meeting of our stockholders or (ii) the first anniversary of the date of grant.

In the first quarter of 2022, our board of directors further amended the Non-Employee Director Compensation Policy and increased the First Director Option to 200,000 shares of common stock and the Subsequent Director Option to 125,000 shares of common stock.

The 2006 Directors’ Stock Option Plan, or 2006 Directors Plan, was terminated by our board of directors and replaced by the 2011 Plan in March 2014. No further grants of stock options were made from the 2006 Directors Plan upon the 2006 Directors Plan’s termination. All outstanding awards granted under the 2006 Directors Plan remain subject to the terms of the 2006 Directors Plan and the individual award agreements thereunder.

The stock options granted to non‑employee directors under the 2006 Directors Plan were nonstatutory stock options, and they expire no later than ten years from the date of grant. The option exercise price was equal to the fair market value of the underlying common stock on the date of grant. The first director option granted to non‑employee directors under the 2006 Directors Plan vested annually over three years upon each anniversary date of appointment to the board of directors. The subsequent director option granted to non‑employee directors on the date of the annual meeting of stockholders in each year during such director’s service on our board of directors under the 2006 Directors Plan vested one year from the date of grant.

In December 2018, our board of directors approved the adoption of the 2018 Inducement Award Plan, or the Inducement Plan, pursuant to which we reserved 3,000,000 shares of Geron common stock (subject to customary adjustments in the event of a change in capital structure) to be used exclusively for grants of inducement awards to individuals who were not previously Geron employees or non-employee directors, other than following a bona fide period of non-employment. In January 2019, February 2020, February 2021, May 2021 and February 2022, our Compensation Committee approved amendments to increase the reserve of shares of our common stock under the Inducement Plan by 5,000,000, 1,300,000, 800,000, 5,000,000 and 1,000,000 shares, respectively. As a result, an aggregate total of 16,100,000 shares of common stock have been reserved under the Inducement Plan.

The Inducement Plan provides for the grant of nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock awards, and all awards under the Inducement Plan are intended to

meet the standards under Rule 5635(c)(4) of the Nasdaq Listing Rules. The terms and conditions of the Inducement Plan and the inducement awards to be granted thereunder are substantially similar to our stockholder-approved 2018 Plan.

In October 2018, our board of directors adopted a Directors’ Market Value Stock Purchase Plan, or the Directors Market Plan. A total of 1,000,000 shares of Geron common stock has been reserved for the Directors Market Plan. Under the Directors Market Plan, non-employee directors may purchase shares of Geron common stock at the prevailing market price on the purchase date with cash compensation payable to them for their services as a board member. As stated in Geron’s Non-Employee Director Compensation Policy, each non-employee director receives annual cash compensation, payable quarterly in arrears, for their services on the board and various committees of the board. As provided in the Non-Employee Director Compensation Policy, a non-employee director may elect to receive fully vested shares of common stock in lieu of cash and such shares shall be issuable from the Directors Market Plan.

For the years ended December 31, 2021, 2020 and 2019, we issued 20,783, 17,986, and 29,150 shares of common stock, respectively, from the Directors Market Plan. The weighted average grant date fair value of stock granted during the years ended December 31, 2021, 2020 and 2019 was $1.38, $1.60 and $1.50 per share, respectively. The total fair value of vested stock grants during 2021, 2020 and 2019 was $29,000, $29,000 and $44,000, respectively.

Aggregate stock option and award activity for the 2011 Plan, 2018 Plan, 2006 Directors Plan, Inducement Plan and Directors Market Plan is as follows:

					Outstanding Stock Options
											Weighted Average		Aggregate
	Shares								Weighted Average		Remaining		Intrinsic
	Available				Number of				Exercise Price		Contractual Life		Value
	For Grant				Shares				Per Share		(In years)		(In thousands)
Balance at December 31, 2020		7,257,747				43,663,691			$	2.12
Additional shares authorized		18,300,000				—			$	—
Stock options granted		(9,562,106	)			9,562,106			$	1.81
Awards granted		(20,783	)			—			$	—
Stock options exercised		—				(451,853	)		$	1.23
Stock options cancelled/forfeited/expired		2,788,535				(2,821,535	)		$	2.31
Balance at December 31, 2021		18,763,393		⁽¹⁾		49,952,409		⁽²⁾	$	2.06		6.09	$	890
Stock options exercisable at December 31, 2021						30,459,136			$	2.35		4.82	$	547
Stock options fully vested and expected to vest at December 31, 2021						49,085,603			$	2.06		6.06	$	878

The aggregate intrinsic value in the preceding table represents the total intrinsic value, based on Geron’s closing stock price of $1.22 per share as of December 31, 2021, which would have been received by the option holders had all the option holders exercised their stock options as of that date.

We have not granted any stock options with an exercise price below or greater than the fair market value of our common stock on the date of grant in 2021, 2020, and 2019. As of December 31, 2021, 2020 and 2019, there were 30,459,136, 25,721,508 and 19,915,713 exercisable stock options outstanding at weighted average exercise prices per share of $2.35, $2.54 and $2.86, respectively.

The total pretax intrinsic value of stock options exercised during 2021, 2020, and 2019 was $93,000, $17,000 and $80,000, respectively. Cash received from the exercise of stock options in 2021, 2020, and 2019 totaled approximately $556,000, $25,000 and $163,000, respectively.

In March 2014, our board of directors adopted the 2014 Employee Stock Purchase Plan, or 2014 Purchase Plan. The 2014 Purchase Plan was approved by our stockholders in May 2014. The 2014 Purchase Plan replaced the 1996 Employee Stock Purchase Plan, or 1996 Purchase Plan, which was terminated effective as of the date the 2014 Purchase Plan was approved by our stockholders. Under the 2014 Purchase Plan, we are authorized to sell to eligible employees up to an aggregate of 1,000,000 shares of Geron common stock. As of December 31, 2021, an aggregate of 531,697 shares of our common stock have been issued under the 2014 Purchase Plan since its adoption.

The 2014 Purchase Plan is comprised of a series of offering periods, each with a maximum duration (not to exceed 12 months) with new offering periods commencing on January 1st and July 1st of each year. The date an employee enters the offering period will be designated as the entry date for purposes of that offering period. An employee may participate only in one offering period at a time. Each offering period consists of two consecutive purchase periods of six months’ duration, with the last day of such period designated a purchase date.

Under the terms of the 2014 Purchase Plan, employees can choose to have up to 10% of their annual salary withheld to purchase our common stock. An employee may not make additional payments into such account or increase the withholding percentage during the offering period.

The purchase price per share at which common stock is purchased by the employee on each purchase date within the offering period is equal to 85% of the lower of (i) the fair market value per share of Geron common stock on the employee’s entry date into that offering period or (ii) the fair market value per share of Geron common stock on the purchase date. If the fair market value per share of Geron common stock on the purchase date is less than the fair market value at the beginning of the offering period, a new 12 month offering period will automatically begin on the first business day following the purchase date with a new fair market value.

We measure and recognize compensation expense for all share‑based payment awards made to employees and directors, including employee stock options, restricted stock awards and employee stock purchases, based on grant‑date fair values for these instruments. We use the Black Scholes option‑pricing model to estimate the grant‑date fair value of our service-based and performance-based stock options and employee stock purchases. The fair value for service‑based restricted stock awards is determined using the fair value of our common stock on the date of grant.

As stock‑based compensation expense recognized on the statements of operations for the years ended December 31, 2021, 2020 and 2019 is based on awards ultimately expected to vest, it has been reduced for estimated forfeitures, but at a minimum, reflects the grant‑date fair value of those awards that actually vested in the period. Forfeitures have been estimated at the time of grant based on historical data and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

In 2021, 2019 and 2018, our board of directors awarded 550,000, 1,000,000 and 4,500,000 performance-based stock options, respectively, to certain employees. These performance-based stock options are included in the outstanding stock options table above. Performance-based stock options vest only upon achievement of discrete strategic milestones. Stock-based compensation expense for performance-based stock options is recognized over the period from the date the performance condition is determined to be probable of occurring through the date the applicable condition is expected to be met and is reduced for estimated forfeitures, as applicable. If the performance condition is not considered probable of being achieved, no stock-based compensation expense is recognized until such time as the performance condition is considered probable of being achieved, if ever. None of the performance-based stock options have vested.

We recognize stock‑based compensation expense for service-based stock options on a straight‑line basis over the requisite service period, which is generally the vesting period. We have not recognized any stock-based compensation expense for performance-based stock options on our statements of operations for the years ended December 31, 2021, 2020 and 2019, as the achievement of the specified strategic milestones was not considered probable during that time. The following table summarizes the stock‑based compensation expense related to

service-based stock options and employee stock purchases for the years ended December 31, 2021, 2020 and 2019 which was allocated as follows:

	Year Ended December 31,
(In thousands)	2021		2020		2019
Research and development	$	3,597	$	2,337	$	1,640
General and administrative		4,483		4,558		4,439
Stock-based compensation expense included in operating expenses	$	8,080	$	6,895	$	6,079

The fair value of stock options granted in 2021, 2020, and 2019 has been estimated at the date of grant using the Black Scholes option‑pricing model with the following assumptions:

The fair value of employee stock purchases in 2021, 2020, and 2019 has been estimated using the Black Scholes option‑pricing model with the following assumptions:

Dividend yield is based on historical cash dividend payments and Geron has paid no cash dividends to date. The expected volatility range is based on historical volatilities of our stock, since traded options on Geron common stock do not correspond to option terms and the trading volume of options is limited. The risk‑free interest rate range is based on the U.S. Zero Coupon Treasury Strip Yields for the expected term in effect on the date of grant for an award. The expected term of stock options is derived from actual historical exercise and post‑vesting cancellation data and represents the period of time that stock options granted are expected to be outstanding. The expected term of employees’ purchase rights is equal to the purchase period.

Based on the Black Scholes option‑pricing model, the weighted average estimated fair value of stock options granted during the years ended December 31, 2021, 2020 and 2019 was $1.17, $0.88 and $0.94 per share, respectively. The weighted average estimated fair value of employees’ purchase rights for the years ended December 31, 2021, 2020 and 2019 was $0.56, $0.62 and $0.66 per share, respectively. As of December 31, 2021, total compensation cost related to unvested share‑based payment awards not yet recognized, net of estimated forfeitures and assuming no probability of achievement for outstanding performance-based stock options, was $12,341,000, which is expected to be recognized over the next 28 months on a weighted‑average basis.

We grant stock options to consultants from time to time in exchange for services performed for us. In general, the stock options vest over the contractual period of the consulting arrangement. The fair value of stock options held by consultants is recorded as operating expenses over the vesting term of the respective equity awards. With the adoption of Accounting Standards Update 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, or ASU 2018-07, in the first quarter of 2019, the measurement date of stock options granted to consultants was fixed at the grant date. We recorded stock‑based compensation expense of $62,000, $56,000 and $24,000 for the vested portion of the fair value of stock options held by consultants in 2021, 2020, and 2019, respectively.

Common stock reserved for future issuance as of December 31, 2021 is as follows: