Stock-based compensation expense is estimated as of the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which generally represents the vesting period. The Company estimates the fair value of its stock options using the Black-Scholes option-pricing model. The weighted-average assumptions used to determine the fair value of the stock option grants is as follows:

The Company’s Board of Directors adopted the Paratek Pharmaceuticals, Inc. 2015 Equity Incentive Plan, or the 2015 Plan, which was approved by Company stockholders at the annual meeting of shareholders held on June 9, 2015. As of March 31, 2022, there are 274,050 shares available for future issuance under the 2015 Plan.

The Company recognizes the stock-based compensation expense of awards subject to performance-based vesting conditions over the requisite service period, to the extent achievement of the performance condition is deemed probable relative to targeted performance using the accelerated attribution method. A change in the requisite service period that does not change the estimate of the total stock-based compensation expense (i.e., it does not affect the grant-date fair value or quantity of awards to be recognized) is recognized prospectively over the remaining requisite service period.

During the three months ended March 31, 2022, the Company’s Board of Directors granted 103,860 stock options and 2,730,940 RSUs to directors, executives, and employees of the Company under the 2015 Plan. The stock option awards are subject to time-based vesting over a period of one to four years. The RSU awards granted to executives in March 2022 are subject to time-based vesting, with 1/3 of the shares vesting on December 10, 2022, and an additional 1/3 of the shares vesting on the succeeding two anniversaries of such date. The RSU awards granted to non-executive employees of the Company during March 2022 are subject to time-based vesting, with 1/3 of the shares vesting on February 16, 2023, and an additional 1/3 of the shares vesting on the succeeding two anniversaries of such date.

The March 2022 grants also included performance-based RSU, or PRSU, awards to certain executives and employees of the Company, which will vest as follows: (a) 35/55 on certain net product revenue achievements, (b) 10/55 upon BARDA's purchase of the second NUZYRA procurement, and (c) 10/55 on certain business achievements. Since the Company believes it is probable that milestone (a) and (b) above will be achieved, the Company recognized an insignificant amount of stock-based compensation expense for the performance condition during the three months ended March 31, 2022 using the accelerated attribution method.

The Company’s Board of Directors adopted the Paratek Pharmaceuticals, Inc. 2015 Inducement Plan, or the 2015 Inducement Plan, in accordance with Nasdaq Rule 5635(c)(4), reserving 360,000 shares of common stock solely for the grant of inducement stock options to employees entering into employment or returning to employment after a bona fide period of non-employment with the Company. The Company has not made any grants under the 2015 Inducement Plan since December 31, 2015. Although the Company does not currently anticipate the issuance of additional grants under the 2015 Inducement Plan, as of March 31, 2022, 341,500 shares remain available for grant under that plan, as well as any shares underlying outstanding stock options that may become available for grant pursuant to the plan’s terms. It is therefore possible that the Company may, based on the business and recruiting needs of the Company, issue additional stock options under the 2015 Inducement Plan.

In June 2017, the Company’s Board of Directors adopted the Paratek Pharmaceuticals, Inc. 2017 Inducement Plan, or the 2017 Inducement Plan, in accordance with Nasdaq Rule 5635(c)(4), reserving 550,000 shares of common stock solely for the grant of inducement stock options and RSU awards to employees entering into employment or returning to employment after a bona fide period of non-employment with the Company. In October 2018 and March 2022, the Company’s Board of Directors approved the reserve of an additional 500,000 shares and 750,000 shares, respectively, for the 2017 Inducement Plan, for a total of 1,800,000 shares reserved for issuance under it. During the three months ended March 31, 2022, the Company’s Board of Directors granted 43,800 stock options and 48,900 RSUs to employees of the Company under the 2017 Inducement Plan. The stock option awards are subject to time-based vesting over a period of one to four years. The RSU awards are generally subject to time-based vesting, with 100% of the shares of common stock subject to the RSU award vesting three years from the grant date. As of March 31, 2022, 970,277 shares remain available for grant under the 2017 Inducement Plan, as well as any shares underlying awards that may become available for grant pursuant to the plan’s terms.


	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2021	2,051,484	$	10.92	5.12	$	303
Granted	147,660	$	3.20
Exercised	(1,646)	$	3.58
Cancelled or forfeited	(33,816)	$	15.63
Outstanding at March 31, 2022	2,163,682	$	10.32	5.19	$	—
Exercisable at March 31, 2022	1,775,194	$	11.56	4.33	$	—

In June 2009, at the annual meeting of stockholders, the stockholders of the Company approved the 2009 Employee Stock Purchase Plan, or the 2009 ESPP. As of March 31, 2022, 36,539 shares were available for issuance under the 2009 ESPP. Since the merger involving privately-held Paratek Pharmaceuticals, Inc. and Transcept Pharmaceuticals, Inc., the Company has not made the 2009 ESPP available to employees.

The Company’s Board of Directors adopted, and in June 2018 Company’s stockholders approved, the Paratek Pharmaceuticals, Inc. 2018 Employee Stock Purchase Plan, or the 2018 ESPP. The 2018 ESPP was amended in October 2018 to change the commencement dates of the offering periods. The maximum aggregate number of shares of the Company’s common stock that may be purchased under the 2018 ESPP is 943,294 shares, or the ESPP Share Pool, subject to adjustment as provided for in the 2018 ESPP. The ESPP Share Pool represented 3% of the total number of shares of our common stock outstanding as of March 31, 2018. The 2018 ESPP allows eligible employees to purchase shares during certain offering periods, which will be 6 -month periods commencing June 1 and ending November 30 and commencing December 1 and ending May 31 of each year. The first offering under the 2018 ESPP was December 1, 2018. As of March 31, 2022, 423,331 shares remained available for issuance under the 2018 ESPP. During the three months ended March 31, 2022, the Company recognized an insignificant amount of stock-based compensation expense related to the 2018 ESPP.

On October 4, 2018, the Company adopted the Revenue Performance Incentive Plan, or the Plan, to grant performance-based cash incentive awards to key employees and consultants of the Company. The Plan provides for an incentive pool of up to $50.0 million, plus accrued interest during the period between the awards’ vesting date and payment dates. Each participant will be allocated a percentage of the incentive pool.

The incentive pool will be divided into two equal tranches with the first tranche vesting upon the Company’s achievement of cumulative net product revenues over $300.0 million by December 31, 2025, or Tranche 1, and the second tranche vesting upon the Company’s achievement of cumulative product revenues over $600.0 million by December 31, 2026, or Tranche 2. Participants will vest annually in each tranche of their awards in four equal installments on December 31, 2019, December 31, 2020, December 31, 2021, and December 31, 2022, subject to their continued employment with the Company through the applicable vesting date. If a participant’s employment terminates prior to December 31, 2022 due to death or disability, the participant will automatically vest in an additional 25% of each tranche of his or her award. Upon the achievement of a Tranche 1 or Tranche 2 milestone (but not a deemed achievement in connection with a change of control), each participant who has remained in continuous employment with the Company through December 31, 2022 will be 100% vested in the applicable tranche. In the event of a change of control of the Company prior to December 31, 2026, participants whose employment has terminated prior to such date will be eligible for payouts under the Plan based on the

Upon the achievement of a Tranche 1 or Tranche 2 milestone (but not a deemed achievement in connection with a change of control), each participant’s payout in respect of the applicable tranche of his or her award will equal (a) the participant’s then-vested percentage, multiplied by (b) $25 million, multiplied by (c) the participant’s individual percentage allocation of the incentive pool.

If a change of control occurs prior to December 31, 2026, and the Tranche 1 milestone was not achieved prior to the change of control, the Tranche 1 milestone will be deemed to be achieved at a percentage equal to the greater of (1) 50% and (2) the cumulative product revenues as of the change of control, divided by $300.0 million. If a change of control occurs prior to December 31, 2026, and the Tranche 2 milestone was not achieved prior to the change of control, the Tranche 2 milestone will be deemed to be achieved at a percentage equal to the greater of (1) 30% and (2) the cumulative product revenues as of the change of control, divided by $600.0 million. A participant’s payout in respect of each tranche of his or her award in a change of control will equal (1) the participant’s then-vested percentage of such tranche, multiplied by (2) the percentage of that tranche’s milestone that has been achieved or is deemed to have been achieved, multiplied by (3)$25.0 million, multiplied by (4) the participant’s individual percentage allocation of the incentive pool.

Amounts that become payable upon achievement of the Tranche 1 milestone will be paid in a lump-sum in the first quarter of 2026 and amounts that become payable upon achievement of the Tranche 2 milestone will be paid in a lump-sum in the first quarter of 2027. In the event of a change of control, any portion of the incentive pool that is earned, but unpaid, or deemed earned in connection with the change of control will be paid at the time of the change of control.

If a change of control occurs prior to the achievement of either or both of the Tranche 1 and Tranche 2 milestones, the awards will remain outstanding and the remaining unpaid portion of the incentive pool applicable to the Tranche 1 or Tranche 2 milestone, as applicable, will be paid following the achievement of either such milestone at the time or times the awards would otherwise be paid out. Any successor in interest to the Company upon or following a change of control will be required to assume all obligations under the Plan.

Awards may be paid out in cash or in a combination of cash and registered securities of equal value (based on the Company’s 20-day trailing average closing common stock price), with the portion paid in registered securities not to exceed 50% of the aggregate payment amount with respect to each tranche; provided, however, that any amounts payable with respect to an award in connection with a change in control will be paid in cash.