On July 1, 2020, the Company’s board of directors approved the 2020 Equity Incentive Plan (“Previous Plan”) which permitted the granting of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards (“RSAs”), restricted stock units (“RSUs”) and other stock-based awards to employees, directors, officers and consultants. As of September 16, 2020, the approval date of the New Plan (as defined below), no additional awards will be granted under the Previous Plan. The terms of the Previous Plan will continue to govern the terms of outstanding equity awards that were granted prior to approval of the New Plan.

On September 16, 2020, the Company’s stockholders approved the 2020 Stock Incentive Plan (“New Plan”), which became effective upon the execution of the underwriting agreement in connection with the IPO. The number of shares of common stock reserved for issuance under the New Plan automatically increases on January 1 of each year, for a period of ten years, from January 1, 2021, continuing through January 1, 2030, by 5% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors (the “New Plan Evergreen Provision”). Pursuant to this provision, on January 1, 2026, the Company increased the number of shares of common stock reserved for issuance under the New Plan by 14,252,582 shares.

Furthermore, on September 16, 2020, the Company’s stockholders approved the Employee Stock Purchase Plan (“ESPP”), which became effective upon the execution of the underwriting agreement in connection with the IPO. The maximum number of shares of common stock that may be issued under the ESPP will not exceed 362,000 shares of common stock, plus the number of shares of common stock that are automatically added on January 1st of each year for a period of up to ten years, commencing on the first January 1 following the IPO and ending on (and including) January 1, 2030, in an amount equal to the lesser of (i) one percent (1.0%) of the total number of shares of capital stock outstanding on December 31st of the preceding calendar year, and (ii) 724,000 shares of common stock. Pursuant to this provision, on January 1, 2026, the Company increased the number of shares of common stock reserved for issuance under the ESPP by 724,000. The Company has issued an aggregate of 358,514 shares of common stock under the ESPP as of December 31, 2025.

On December 15, 2023, the Company’s board of directors adopted the Taysha Gene Therapies, Inc. 2023 Inducement Plan (the “Inducement Plan”). The Inducement Plan was adopted without stockholder approval pursuant to Nasdaq Listing Rule 5635(c)(4). The Board reserved 4,000,000 shares of the Company’s common stock for issuance under the Inducement Plan. On December 12, 2024, the Company reserved an additional 2,000,000 shares of the Company’s common stock for issuance under the Inducement Plan. On November 14, 2025, the Company reserved an additional 3,000,000 shares of the Company’s common stock for issuance under the Inducement Plan.

The only persons eligible to receive grants of Inducement Awards (as defined below) under the Inducement Plan are individuals who satisfy the standards for inducement grants under Nasdaq Listing Rule 5635(c)(4). The Inducement Plan will be administered by the Board and the Company’s Compensation Committee. Inducement Awards may only be granted by: (i) the Compensation Committee, provided such committee is comprised solely of “independent directors” (as defined by Nasdaq Listing Rule 5605(a)(2)) or (ii) a majority of the Company’s “independent directors.” An “Inducement Award” means any right to receive the Company’s common stock, cash or other

property granted under the Inducement Plan (including nonstatutory stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance stock awards, performance cash awards or other stock-based awards).

The number of shares available for grant under the Company’s incentive plans were as follows:


	New			Inducement
	Plan			Plan			Total
Available for grant - January 1, 2024		3,162,725			4,000,000			7,162,725
Plan adjustments and amendments		9,348,009			2,000,000			11,348,009
Grants		(12,442,262	)		(3,774,300	)		(16,216,562	)
Forfeitures		632,958			774,000			1,406,958
Available for grant - December 31, 2024		701,430			2,999,700			3,701,130
Plan adjustments and amendments		10,247,165			3,000,000			13,247,165
Grants		(15,999,976	)		(4,141,600	)		(20,141,576	)
Forfeitures		1,136,093			1,283,950			2,420,043
Available for grant net of reserve - December 31, 2025		(3,915,288	)		3,142,050			(773,238	)

In August 2025, the Company’s board of directors approved the grant of 5,765,000 PSUs (as defined below) under the New Plan that are eligible to vest upon the achievement of various clinical and regulatory performance conditions. The grant of these awards exhausted the existing share reserve under the New Plan, and the Company used 3,915,288 shares of the shares to be issued on January 1, 2026 under the New Plan Evergreen Provision, which is permissible under section 2(c) of the New Plan, which limits the number of shares of common stock that may be issued pursuant to awards but does not limit the granting of awards. The Company increased the shares of common stock reserved for issuance under the New Plan by 14,252,582 on January 1, 2026 pursuant to the New Plan Evergreen Provision.

For the year ended December 31, 2025, 11,005,584 shares of common stock under the New Plan and Inducement Plan were awarded with a weighted-average grant date fair value per share of $1.59. The stock options vest over one to four years and have a ten-year contractual term.

The following weighted-average assumptions were used to estimate the fair value of time-based vesting stock options that were granted during the years ended December 31, 2025 and 2024:


	Year Ended December 31,
	2025			2024
Risk-free interest rate		4.24	%		4.02	%
Expected dividend yield		—			—
Expected term (in years)		6.0			6.1
Expected volatility		89	%		89	%

The following table summarizes time-based vesting stock option activity, during the years ended December 31, 2025 and 2024:


						Weighted
				Weighted		Average		Aggregate
				Average		Remaining		Intrinsic
	Stock			Exercise		Contractual		Value
	Options			Price		Life (in years)		(in thousands)
Outstanding at January 1, 2024		5,960,922			5.75		8.7		1,960
Options granted		11,719,421			2.02
Options exercised		(58,832	)		0.68
Options cancelled or forfeited		(1,327,123	)		2.50
Options expired		(73,783	)		17.01
Outstanding at December 31, 2024		16,220,605		$	3.29		8.7	$	1,967
Options granted		11,005,584			2.09
Options exercised		(629,478	)		1.80
Options cancelled or forfeited		(1,931,407	)		2.00
Options expired		(96,043	)		2.13
Outstanding at December 31, 2025		24,569,261		$	2.90		8.3	$	81,677
Options exercisable at December 31, 2025		8,707,033		$	4.45		7.3	$	26,913

The aggregate intrinsic value in the above table is calculated as the difference between the fair value of the Company’s common stock at the respective reporting date and the exercise price of the stock options. As of December 31, 2025, the total unrecognized

compensation related to unvested time-based vesting stock option awards granted was $21.0 million, which the Company expects to recognize over a weighted-average period of approximately 2.7 years. During the years ended December 31, 2025 and 2024, 629,478 and 58,832 stock options were exercised, respectively.

In February 2023, the Company issued options to purchase 70,235 shares of common stock to employees under the New Plan that contain performance-based vesting conditions, subject to continued employment through each anniversary and achievement of the performance conditions. The grant date fair value of these awards was not material. During the year ended December 31, 2025, 1,065 performance-based stock options were exercised. As of December 31, 2025, 57,281 of the shares subject to the performance-based options were vested and outstanding. No performance-based stock options were exercised during the year ended December 31, 2024.

In May 2023, the Company issued options to purchase 2,166,653 shares of common stock to employees under the New Plan that contain both service and performance-based vesting conditions (the “Original Options”), with a weighted average grant date fair value per share of $0.50. These Original Options were expected to vest over a 3.6 year term if a combination of clinical, regulatory and financing performance conditions were achieved. No compensation expense was recognized in 2023 related to the Original Options as achievement of the performance conditions was not considered probable. The following weighted-average assumptions were used to estimate the fair value of the options granted in February 2023 and the Original Options that were granted in May 2023:

In December 2023, the Company modified all of the Original Options to amend the clinical and regulatory performance conditions and decreased the number of options granted to 1,516,655 (the “Modified Options”). The Company accounted for the changes in award terms as a modification in accordance with ASC 718, Compensation - Stock Compensation. Total compensation cost is equal to the modification date fair value. The Modified Options have a grant date fair value per share of $1.28. The following assumptions were used to estimate the fair value of the Modified Options:

The Modified Options will vest over 3.0 years. The Company recognized stock-based compensation expense of $0.5 million and $1.2 million for the years ended December 31, 2025 and 2024, respectively, related to the Modified Options. As of December 31, 2025, the total unrecognized compensation expense related to the Modified Options was $0.2 million, which the Company expects to recognize over a weighted average period of approximately 1.0 year using the accelerated attribution method. During the year ended December 31, 2025, 123,717 of the Modified Options were exercised. As of December 31, 2025, 1,392,938 of the Modified Options were outstanding, of which 887,386 were vested.

For the year ended December 31, 2025, the Company issued 3,370,992 RSUs to employees under the New Plan. The RSUs are subject to a service-based vesting condition. The service-based RSUs vest in equal annual installments over a one to four-year period. The Company at any time may accelerate the vesting of the RSUs. Such shares are not accounted for as outstanding until they vest.

The Company’s default tax withholding method for RSUs granted prior to 2023 is the sell-to-cover method, in which shares with a market value equivalent to the tax withholding obligation are sold on behalf of the holder of the RSUs upon vesting and settlement to cover the tax withholding liability and the cash proceeds from such sales are remitted by the Company to taxing authorities. For RSUs granted in 2023, the Company’s tax withholding policy allows the RSU holder to choose to either pay cash to the Company for the tax withholding obligation or elect the net withholding method, in which shares with a market equivalent to the tax withholding obligation are withheld and the net shares are issued to the RSU holder. For RSUs granted in 2024 and later, the Company’s tax withholding policy allows the RSU holder to choose to either pay cash to the Company for the tax withholding obligation or to elect the sell-to-cover method, in which shares with a market value equivalent to the tax withholding obligation are sold on behalf of the holder of the RSUs upon vesting and settlement to cover the tax withholding liability and the cash proceeds from such sales are remitted by the Company to taxing authorities. The Company adopted a mandatory sell-to-cover policy for settlement of any outstanding RSUs vesting on or after January 1, 2026.

The Company’s RSU activity for the years ended December 31, 2025 and 2024 was as follows:


				Weighted
				Average
				Grant Date
	Number			Fair Value
	of Shares			per Share
Nonvested at January 1, 2024		375,044		$	6.63
Restricted units granted		4,497,141			1.83
Vested		(323,031	)		7.50
Cancelled or forfeited		—			—
Nonvested at December 31, 2024		4,549,154		$	1.82
Restricted units granted		3,370,992			1.95
Vested		(1,246,218	)		1.94
Cancelled or forfeited		(362,750	)		2.40
Nonvested at December 31, 2025		6,311,178		$	1.78

As of December 31, 2025, the total unrecognized compensation cost related to the unvested RSUs was $8.1 million which is expected to be amortized on a straight-line basis over a weighted-average period of approximately 2.5 years.

In August 2025, the Company issued 5,765,000 performance-based restricted stock units (“PSUs”) to employees under the New Plan that are eligible to vest upon the achievement of certain clinical and regulatory performance conditions. The grant date fair value of the PSUs was $17.3 million, which is expected to be recognized at a point in time when achievement of the underlying performance conditions is considered probable, using management’s best estimates, which consider the inherent risk and uncertainty regarding the future outcomes of the performance conditions. During the year ended December 31, 2025, no compensation expense was recorded related to the PSUs as achievement of the performance conditions was not considered probable. As of December 31, 2025, 5,765,000 of the PSUs were unvested and outstanding.

In February 2022, the Company’s board of directors authorized the first offering under the ESPP. Under the ESPP, eligible employees may purchase shares of Taysha common stock through payroll deductions at a price equal to 85% of the lower of the fair market values of the stock as of the beginning or the end of six-month offering periods. An employee’s payroll deductions under the ESPP are limited to 15% of the employee’s compensation and employees may not purchase more than 1,800 shares of Taysha common stock during any offering period. During the years ended December 31, 2025 and 2024, stock-based compensation expense related to the ESPP was not material.