Zimmer Biomet has share-based compensation plans under which it granted stock options, restricted stock units ("RSUs") and performance-based RSUs. In connection with the distribution, ZimVie employees with outstanding Zimmer Biomet share-based awards received replacement share-based awards. The ratio used to convert the Zimmer Biomet share-based awards was designed to preserve the aggregate intrinsic value of the award immediately after the distribution when compared to the aggregate intrinsic value of the award immediately prior to the distribution. Outstanding RSUs and performance-based RSUs were converted into 0.3 million ZimVie RSUs at a weighted average fair value of $31.55, and outstanding stock options were converted into 2.1 million ZimVie stock options at a weighted average fair value of $14.76. Due to the conversion, ZimVie incurred $21.3 million of incremental share-based compensation expense. Of this amount, $10.3 million was related to unvested and/or unexercised share-based awards and was recognized at the distribution date. The remaining $11.0 million is being recognized over the remainder of the share-based awards' weighted average vesting period of 2.5 years from the date of the distribution.

The ZimVie Inc. 2022 Stock Incentive Plan was established effective as of March 1, 2022, and was amended effective May 12, 2023 (as amended, the "2022 Plan"). A total of 6.0 million shares of common stock are authorized for issuance under the 2022 Plan. Shares issued pursuant to converted Zimmer Biomet share-based awards do not count against this limit. At March 31, 2024, 2.9 million shares were available for future grants and awards under the 2022 Plan. The 2022 Plan provides for the grant of various types of awards including stock options, stock appreciation rights, performance shares, performance units, restricted stock and RSUs. Generally, awards have a three-year vesting period and stock options have a term of ten years. Vesting may accelerate upon retirement after the first anniversary date of the award if certain criteria are met. Additionally, in cases of special circumstances as determined by the Compensation Committee of the Board of Directors, the Compensation Committee may, it its sole discretion, accelerate vesting. We recognize expense on a straight-line basis over the requisite service period, less awards expected to be forfeited using estimated forfeiture rates. Stock options are granted with an exercise price equal to the market price of our common stock on the date of grant, except in limited circumstances where local law may dictate otherwise.

Share-based compensation expense was as follows (in thousands):


	For the Three Months Ended March 31,
	2024			2023
Share-based compensation expense recognized in:
Cost of products sold, excluding intangible asset amortization	$	(18	)	$	265
Research and development		401			422
Selling, general and administrative		3,090			4,154
		3,473			4,841
Tax benefit related to awards		(861	)		(1,209	)
Total expense, net of tax	$	2,612		$	3,632

Share-based compensation expense related to discontinued operations is included in the table above and is disclosed in Note 2.

Stock option activity was as follows:


	Three Months Ended March 31, 2024
				Weighted		Weighted Average
				Average		Remaining		Aggregate
	Number of			Exercise		Contractual		Intrinsic
	Stock Options			Price		Life (Years)		Value (in Millions)
Outstanding at December 31, 2023		2,303,143		$	26.83
Granted		—			—
Exercised		(1,117	)		18.58
Forfeited		(82,798	)		26.10
Outstanding at March 31, 2024		2,219,228		$	26.87		5.5	$	—
Exercisable at March 31, 2024		1,852,652		$	26.72		5.0	$	—

We used a Black-Scholes option-pricing model to determine the fair value of our stock options. For awards granted shortly after the distribution: expected volatility of 52.29% was derived from a peer group's combined historical volatility that was de-levered and re-levered for ZimVie as ZimVie did not have sufficient historical volatility based on the expected term of the underlying options; the expected term of the stock options of 6.0 years was determined using the simplified method; and the risk-free interest rate of 1.94% was determined using the implied yield then available for zero-coupon U.S. government issues with a remaining term approximating the expected life of the options. The dividend yield was zero as ZimVie has no plans to pay a dividend for the foreseeable future.

Aggregate intrinsic value was negligible at March 31, 2024. At March 31, 2024, we had unrecognized share-based compensation cost related to unvested stock options of $4.2 million, which is expected to be amortized over the remaining weighted average vesting period of approximately 1.1 years.

RSU activity was as follows:


	Three Months Ended March 31, 2024
				Weighted
				Average
	Number of			Grant Date
	RSUs			Fair Value
Outstanding at December 31, 2023		1,942,210		$	15.13
Granted		738,939			17.58
Vested		(278,865	)		28.13
Forfeited		(132,728	)		14.22
Outstanding at March 31, 2024		2,269,556		$	14.38

RSUs outstanding at March 31, 2024 included 326,321 RSUs (at target) with performance-based vesting provisions ("PRSUs"). PRSUs may vest from 0-150% of target based on the level of achievement of pre-defined performance metrics. PRSUs are payable in common shares and do not have the right to vote until vested. Compensation expense related to PRSUs is recognized over a 36-month cliff vesting period, and is adjusted as needed for changes in the projected level of achievement of the performance metrics.

At March 31, 2024, we had unrecognized share-based compensation cost related to unvested RSUs of $22.1 million, which is expected to be amortized into earnings over the remaining weighted average vesting period of approximately 1.5 years. The total fair value of RSUs granted during the three months ended March 31, 2024 and 2023 was $13.0 million and negligible, respectively. The total fair value of RSUs that vested during the three months ended March 31, 2024 and 2023 was $7.8 million and $6.1 million, respectively.