Pay vs Performance Disclosure - USD ($)

12 Months Ended

Dec. 31, 2022

Dec. 31, 2021

Pay vs Performance Disclosure [Table]

Pay Versus Performance Table

As required by Section 953(a) of the Dodd-Frank Wall Street Reform and Consumer Protection Act, and Item 402(v) of Regulation S-K, we are providing the following information about the relationship between executive compensation actually paid and certain financial performance of the Company. For information on our executive compensation program and the Compensation Committee’s approach, refer to the above Narrative Disclosure to Summary Compensation Table and Outstanding Equity Awards Table.


Year(1)	Summary Compensation Table Total for PEO(2)	Compensation Actually Paid to PEO(3)	Average Summary Compensation Table Total for Non-PEO NEOs(4)	Average Compensation Actually Paid to Non-PEO NEOs(5)	Value of Initial Fixed $100 Investment Based On Total Shareholder Return(6)	Net Income (Loss) (In Thousands)(7)
2022	$2,997,203	$5,898,457	$1,361,162	$2,480,002	152.20	($141,901)
2021	$2,056,987	$1,340,341	$1,155,449	$832,837	76.73	($116,112)

______________________________

(1) For each of the two years presented in the above table, John Scarlett was our Principal Executive Officer (“PEO”) and our Non-PEO Named Executive Officers (“Non-PEO NEOs”) were Olivia Bloom and Andrew Grethlein.

(2) See the Summary Compensation Table above for detail on the Summary Compensation Table total compensation for our PEO for each fiscal year covered in the table. The average compensation for the Non-PEO NEOs for 2022 was calculated using the Summary Compensation Table above. The average compensation for the Non-PEO NEOs for 2021 was calculated using the Summary Compensation Table as disclosed in our proxy statement filed with the Securities and Exchange Commission in calendar year 2022.

(3) For purposes of this table, the compensation actually paid (“Compensation Actually Paid”, or “CAP”) has been computed in accordance with Item 402(v) of Regulation S-K under the Exchange Act and do not reflect the actual amount of compensation earned by or paid to the NEOs during the applicable year. These amounts reflect total compensation as reflected in the above Summary Compensation Table for the applicable year less the grant date fair values of stock option awards included in the “Option Awards” column of the Summary Compensation Table for the Named Executive Officer for the applicable year, and adjusted as follows for each stock option award granted to each Named Executive Officer:


Year	Reported Summary Compensation Table Total for PEO	Reported Value of Equity Awards (a)	Equity Award Adjustments (b)	Reported Change in the Actuarial Present Value of Pension Benefits (c)	Pension Benefit Adjustments (d)	Compensation Actually Paid to PEO
2022	$2,997,203	$1,468,740	$4,369,994	$—	$—	$5,898,457
2021	$2,056,987	$796,740	$80,094	$—	$—	$1,340,341

____________________

(a) The grant date fair value of equity awards represents the total of the amounts reported in the “Stock Awards” and “Option Awards” columns in the Summary Compensation Table for the applicable year.

(b) The equity award adjustments for each applicable year include the addition (or subtraction, as applicable) of the following: (i) the year-end fair value of any equity awards granted in the applicable year that are outstanding and unvested as of the end of the year; (ii) the amount of change as of the end of the applicable year (from the end of the prior fiscal year) in fair value of any awards granted in prior years that are outstanding and unvested as of the end of the applicable year; (iii) for awards

that are granted and vest in the same applicable year, the fair value as of the vesting date; (iv) for awards granted in prior years that vest in the applicable year, the amount equal to the change as of the vesting date (from the end of the prior fiscal year) in fair value; (v) for awards granted in prior years that are determined to fail to meet the applicable vesting conditions during the applicable year, a deduction for the amount equal to the fair value at the end of the prior fiscal year; and (vi) the dollar value of any dividends or other earnings paid on stock or option awards in the applicable year prior to the vesting date that are not otherwise reflected in the fair value of such award or included in any other component of total compensation for the applicable year. The valuation assumptions used to calculate fair values did not materially differ from those disclosed at the time of grant. The amounts deducted or added in calculating the equity award adjustments are as follows:


Year	Year End Fair Value of Equity Awards	Year over Year Change in Fair Value of Outstanding and Unvested Equity Awards	Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year	Year over Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year	Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year	Value of Dividends or other Earnings Paid on Stock or Option Awards not Otherwise Reflected in Fair Value or Total Compensation	Total Equity Award Adjustments
2022	$3,124,188	$381,355	$629,125	$235,326	$—	$—	$4,369,994
2021	$327,750	($267,010)	$110,000	($90,646)	$—	$—	$80,094

(4) The dollar amounts reported in column (d) represent the average of the amounts reported for the Company’s Non-PEO NEOs as a group in the “Total” column of the Summary Compensation Table in each applicable year. The names of each of the Non-PEO NEOs included for purposes of calculating the average amounts in each applicable year are as follows: (i) for 2022, Olivia K. Bloom and Andrew J. Grethlein; and (ii) for 2021, Olivia K. Bloom, Andrew J Grethlein, Aleksandra Rizo, Anil Kapur and Melissa A. Kelly Behrs.

(5) The dollar amounts reported in column (e) represent the average amount of Compensation Actually Paid to our Non-PEO NEOs as a group, as computed in accordance with Item 402(v) of Regulation S-K. The dollar amounts do not reflect the actual average amount of compensation earned by or paid to the non-PEO NEOs as a group during the applicable year. The following adjustments were made to average total compensation for the Non-PEO NEOs as a group for each year to determine the compensation actually paid, using the same methodology described above in Note 3:


Year	Average Reported Summary Compensation Table Total for Non-PEO NEOs	Average Reported Value of Equity Awards	Average Equity Award Adjustments (a)	Average Compensation Actually Paid to Non-PEO NEOs
2022	$1,361,162	$524,550	$1,643,390	$2,480,002
2021	$1,155,449	$398,370	$75,758	$832,837

______________

(a) The amounts deducted or added in calculating the total average equity award adjustments are as follows:


Year	Average Year End Fair Value of Equity Awards	Average Year over Year Change in Fair Value of Outstanding and Unvested Equity Awards	Average Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year	Average Year over Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year	Average Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year	Average Value of Dividends or other Earnings Paid on Stock or Option Awards not Otherwise Reflected in Fair Value or Total Compensation	Average Total Equity Award Adjustments
2022	$1,145,938	$185,608	$224,688	$87,156	$—	$—	$1,643,390
2021	$163,875	($115,972)	55,000	(27,145)	$—	$—	75,758

(6) Total Shareholder Return represents the return on a fixed investment of $100 in Geron common stock for the period beginning on the last trading day of 2020 through the last trading day of the applicable fiscal year.

(7) The dollar amounts reported represent the amount of net income (loss) reflected in the Company’s audited financial statements for the applicable year.

Named Executive Officers, Footnote [Text Block]

For each of the two years presented in the above table, John Scarlett was our Principal Executive Officer (“PEO”) and our Non-PEO Named Executive Officers (“Non-PEO NEOs”) were Olivia Bloom and Andrew Grethlein.The dollar amounts reported in column (d) represent the average of the amounts reported for the Company’s Non-PEO NEOs as a group in the “Total” column of the Summary Compensation Table in each applicable year. The names of each of the Non-PEO NEOs included for purposes of calculating the average amounts in each applicable year are as follows: (i) for 2022, Olivia K. Bloom and Andrew J. Grethlein; and (ii) for 2021, Olivia K. Bloom, Andrew J Grethlein, Aleksandra Rizo, Anil Kapur and Melissa A. Kelly Behrs.

PEO Total Compensation Amount

$ 2,997,203

$ 2,056,987

PEO Actually Paid Compensation Amount

$ 5,898,457

1,340,341

Adjustment To PEO Compensation, Footnote [Text Block]


Year	Reported Summary Compensation Table Total for PEO	Reported Value of Equity Awards (a)	Equity Award Adjustments (b)	Reported Change in the Actuarial Present Value of Pension Benefits (c)	Pension Benefit Adjustments (d)	Compensation Actually Paid to PEO
2022	$2,997,203	$1,468,740	$4,369,994	$—	$—	$5,898,457
2021	$2,056,987	$796,740	$80,094	$—	$—	$1,340,341

____________________


Year	Year End Fair Value of Equity Awards	Year over Year Change in Fair Value of Outstanding and Unvested Equity Awards	Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year	Year over Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year	Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year	Value of Dividends or other Earnings Paid on Stock or Option Awards not Otherwise Reflected in Fair Value or Total Compensation	Total Equity Award Adjustments
2022	$3,124,188	$381,355	$629,125	$235,326	$—	$—	$4,369,994
2021	$327,750	($267,010)	$110,000	($90,646)	$—	$—	$80,094

Non-PEO NEO Average Total Compensation Amount

$ 1,361,162

1,155,449

Non-PEO NEO Average Compensation Actually Paid Amount

$ 2,480,002

832,837

Adjustment to Non-PEO NEO Compensation Footnote [Text Block]

The dollar amounts reported in column (e) represent the average amount of Compensation Actually Paid to our Non-PEO NEOs as a group, as computed in accordance with Item 402(v) of Regulation S-K. The dollar amounts do not reflect the actual average amount of compensation earned by or paid to the non-PEO NEOs as a group during the applicable year. The following adjustments were made to average total compensation for the Non-PEO NEOs as a group for each year to determine the compensation actually paid, using the same methodology described above in Note 3:


Year	Average Reported Summary Compensation Table Total for Non-PEO NEOs	Average Reported Value of Equity Awards	Average Equity Award Adjustments (a)	Average Compensation Actually Paid to Non-PEO NEOs
2022	$1,361,162	$524,550	$1,643,390	$2,480,002
2021	$1,155,449	$398,370	$75,758	$832,837

______________

(a) The amounts deducted or added in calculating the total average equity award adjustments are as follows:


Year	Average Year End Fair Value of Equity Awards	Average Year over Year Change in Fair Value of Outstanding and Unvested Equity Awards	Average Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year	Average Year over Year Change in Fair Value of Equity Awards Granted in Prior Years that Vested in the Year	Average Fair Value at the End of the Prior Year of Equity Awards that Failed to Meet Vesting Conditions in the Year	Average Value of Dividends or other Earnings Paid on Stock or Option Awards not Otherwise Reflected in Fair Value or Total Compensation	Average Total Equity Award Adjustments
2022	$1,145,938	$185,608	$224,688	$87,156	$—	$—	$1,643,390
2021	$163,875	($115,972)	55,000	(27,145)	$—	$—	75,758

Compensation Actually Paid vs. Total Shareholder Return [Text Block]

Compensation Actually Paid and Cumulative TSR

The following graph sets forth the relationship between Compensation Actually Paid to our PEO, the average of Compensation Actually Paid to our Non-PEO NEOs, and the Company’s cumulative TSR over the two most recently completed fiscal years.

Compensation Actually Paid vs. Net Income [Text Block]

Compensation Actually Paid and Net Income (Loss)

The following graph sets forth the relationship between Compensation Actually Paid to our PEO, the average of Compensation Actually Paid to our Non-PEO NEOs, and the Company’s net income (loss) over the two most recently completed fiscal years.

Total Shareholder Return Amount

$ 152.20

76.73

Net Income (Loss)

$ (141,901,000)

(116,112,000)

PEO Name

John Scarlett

Additional 402(v) Disclosure [Text Block]

For purposes of this table, the compensation actually paid (“Compensation Actually Paid”, or “CAP”) has been computed in accordance with Item 402(v) of Regulation S-K under the Exchange Act and do not reflect the actual amount of compensation earned by or paid to the NEOs during the applicable year. These amounts reflect total compensation as reflected in the above Summary Compensation Table for the applicable year less the grant date fair values of stock option awards included in the “Option Awards” column of the Summary Compensation Table for the Named Executive Officer for the applicable year, and adjusted as follows for each stock option award granted to each Named Executive Officer: The dollar amounts reported in column (e) represent the average amount of Compensation Actually Paid to our Non-PEO NEOs as a group, as computed in accordance with Item 402(v) of Regulation S-K. The dollar amounts do not reflect the actual average amount of compensation earned by or paid to the non-PEO NEOs as a group during the applicable year. The following adjustments were made to average total compensation for the Non-PEO NEOs as a group for each year to determine the compensation actually paid, using the same methodology described above in Note 3:

PEO [Member] | Reported Value of Equity Awards [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

$ 1,468,740

796,740

PEO [Member] | Equity Award Adjustments [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

4,369,994

80,094

PEO [Member] | Equity Awards Unvested [Member]

Pay vs Performance Disclosure [Table]