STOCK-BASED COMPENSATION AND EMPLOYEE RETIREMENT PLANS
Stock-Based Compensation Plans
The Company incurred stock-based compensation expenses of $7.8 million and $9.3 million for the years ended December 31, 2024 and 2023, respectively.
Equity Incentive Plans
The following table contains information about the Company's equity incentive plans:
December 31, 2024December 31, 2023
Title of PlanGroup EligibleType of Award Granted (or to be Granted)Awards Outstanding
Additional Awards Available for Grant
Awards Outstanding
Additional Awards Available for Grant
Keryx Equity Plans(1)(2)
Employees, directors and consultants
Common stock options and RSUs
163,765 — 232,203 — 
Akebia Therapeutics, Inc. 2014 Incentive Plan, as amended (2) (3)
(the 2014 Plan)
(replaces 2008 Plan)
Employees, directors, consultants and advisors
Common stock options, RSUs, SARs and performance awards
11,559,708 — 15,311,501 — 
Akebia Therapeutics, Inc. 2023 Stock Incentive Plan(3) (the 2023 Plan)
(replaces 2014 Plan)
Employees, officers, directors, consultants and advisors
Common stock options, SARs, restricted stock, unrestricted stock, RSUs, performance awards, other share-based awards and dividend equivalents
10,390,642 11,340,648 1,712,400 17,382,722 
(1)     The Keryx Equity Plans consist of the Keryx Biopharmaceuticals, Inc. 1999 Share Option Plan, Keryx Biopharmaceuticals, Inc., as amended, the 2004 Long-Term Incentive Plan, as amended, the Keryx Biopharmaceuticals, Inc. 2007 Incentive Plan, the Keryx Biopharmaceuticals Inc. Amended and Restated 2013 Incentive Plan and the Keryx Biopharmaceuticals, Inc. 2018 Equity Incentive Plan.
(2)     New awards are no longer being granted under these plans.
(3)     This table includes the following inducement awards that are subject to the terms and conditions of the applicable plan but were granted as inducement awards consistent with Nasdaq Listing Rule 5635(c)(4) and not under the applicable plan: 1,151,127 options outstanding under the 2014 Plan and 2,534,775 options outstanding under the 2023 Plan as of December 31, 2024 and 1,616,019 options outstanding under the 2014 Plan and 794,000 options outstanding under the 2023 Plan as of December 31, 2023.
Common Stock Options and Stock Appreciation Rights
During the year ended December 31, 2024, the Company granted 3,117,500 options to employees and 315,000 options to directors under the 2023 Plan. Options and SARs granted by the Company generally vest over periods of between 12 and 48 months, subject, in each case, to the individual’s continued service through the applicable vesting date. Options and SARs generally vest either 100% on the first anniversary of the grant date or in installments of (i) 25% at the one year anniversary and (ii) 12 equal quarterly installments beginning after the one year anniversary of the grant date, subject to the individual’s continuous service with the Company. Options and SARs generally expire ten years after the date of grant.
The Company also maintains an inducement award program with a share pool that is separate from the Company's equity plans under which inducement awards may be granted consistent with Nasdaq Listing Rule 5635(c)(4). During the year ended December 31, 2024, the Company granted 1,911,550 options to purchase shares of the Company’s common stock to new hires as inducements to such employees entering into employment with the Company, of which 1,904,550 options remained outstanding at December 31, 2024.
The Company grants annual service-based stock options to employees and directors and SARs to certain executives under the 2023 Plan and previously granted options under the 2014 Plan. In addition, the Company issues common stock options to directors, new hires and occasionally to other employees not in connection with the annual grant process.
Finally, the Company grants performance-based stock options which generally vest in connection with the achievement of specified commercial, regulatory and corporate milestones. The performance-based stock options also generally feature a time-based vesting component. The expense recognized for these awards is based on the grant date fair value of the Company’s common stock multiplied by the number of options granted and recognized over time based on the probability of meeting such commercial, regulatory and corporate milestones.
The combined stock option activity for the year ended December 31, 2024, is as follows:
 Stock OptionsWeighted-Average
Exercise Price
Weighted-Average
Contractual Life
(years)
Aggregate Intrinsic Value
(in thousands)
Outstanding, December 31, 202313,312,835 $4.20 7.27 years$2,680 
Granted5,344,050 $1.57 
Exercised(444,239)$0.87 
Expired(865,478)$10.03 
Canceled and forfeited(662,843)$3.09 
Outstanding at December 31, 2024
16,684,325 $3.19 7.17 years$6,797 
Exercisable at December 31, 2024
8,636,721 $4.80 5.72 years$2,885 
Vested and expected to vest at December 31, 2024
16,684,325 $3.19 7.17 years$6,797 
The intrinsic value of options exercised during the year ended December 31, 2024 was $0.4 million. There was immaterial intrinsic value of options exercised during the year ended December 31, 2023, as the value of options exercised in 2023 was immaterial. The fair value of options that vested during the years ended December 31, 2024 and 2023 was $3.7 million and $6.4 million, respectively. As of December 31, 2024, there was approximately $7.7 million of unrecognized compensation cost related to common stock options outstanding under the Company’s 2023 Plan or the 2014 Plan or made pursuant to the Company's inducement award program, which is expected to be recognized over a weighted average period of 2.67 years.
Restricted Stock Units
Generally, RSUs, granted by the Company vest in one of the following ways: (i) 100% of each RSU grant vests on the first anniversary of the grant date, (ii) one third of each RSU grant vests on the first, second and third anniversaries of the grant date, (iii) 50% of each RSU grant vests on the first anniversary and 25% of each RSU grant vests every six months after the one year anniversary of the grant date, or (iv) one third of each RSU grant vests on the first anniversary of the grant date and the remaining two thirds vests in eight substantially equal quarterly installments beginning after the one year anniversary, subject, in each case, to the individual’s continued service through the applicable vesting date. The grant-date fair value of the RSUs is recognized as expense on a straight-line basis. The Company determines the fair value of the RSUs based on the closing price of the common stock on the date of the grants.
The Company also periodically grants performance-based restricted stock units, or PSUs, to employees under the 2023 Plan and previously granted PSUs under the 2014 Plan. The PSUs granted by the Company generally vest in connection with the achievement of specified commercial, regulatory and corporate milestones. The PSUs also generally feature a time-based vesting component. The expense recognized for these awards is based on the grant date fair value of the Company’s common stock multiplied by the number of units granted and recognized over time based on the probability of meeting such commercial, regulatory and corporate milestones.
RSU and PSU activity is as follows:
2014 Plan2023 Plan
Number of Shares
Weighted Average Grant Date Fair Value
Number of Shares
Weighted Average Grant Date Fair Value
Unvested as of December 31, 2023
3,339,869 $1.30603,400 $1.48
Granted— $0.003,993,400 $1.59
Vested(1,742,807)$1.58(356,733)$1.36
Forfeited and canceled(275,639)$1.29(131,700)$1.68
Unvested as of December 31, 2024
1,321,423 $0.954,108,367 $1.59
The total fair value of RSUs and PSUs that vested during 2024 and 2023 (measured on the date of vesting) was $3.2 million and $8.4 million, respectively. As of December 31, 2024, there was approximately $5.1 million of unrecognized compensation cost related to RSUs and PSUs, which is expected to be recognized over a weighted average period of 1.91 years.
Employee Stock Purchase Plan
On June 6, 2019, the Company’s stockholders approved the Amended and Restated 2014 Employee Stock Purchase Plan, or ESPP. Under the ESPP substantially all employees may voluntarily enroll to purchase shares of the Company’s 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 the six-month offering period. An employee's payroll deductions under the ESPP are limited to 15% of the employee's compensation, and an employee may not purchase more than $25,000 worth of stock during any calendar year. In addition, an employee may not purchase more than 1,500 shares in any six-month offering period. As of December 31, 2024 and 2023, a total of 4,448,069 and 4,637,801 shares of the Company's common stock were available for future issuance under the ESPP, respectively. The Company issued 189,732 shares during the year ended December 31, 2024.
Stock-Based Compensation Expense
The Black-Scholes option pricing model is used to estimate the fair value of the common stock options. The weighted-average assumptions used in calculating the fair values of the rights to acquire stock under the 2023 Plan, the 2014 Plan and inducement awards were as follows:
 Years ended December 31,
Common Stock Options
2024
2023
Risk-free interest rate3.60%-4.66%3.54%-4.81%
Expected volatility109.98%-119.81%100.97%-111.71%
Expected term (years)5.51-6.255.51-6.25
Expected dividend yield —%—%
Weighted average grant date fair value
$1.36$0.69
The Company has classified stock-based compensation in its consolidated statements of operations and comprehensive loss as follows (in thousands):
 Years ended December 31,
 20242023
Cost of goods sold$399 $267 
Research and development1,498 1,964 
Selling, general and administrative5,840 6,456 
Restructuring38 630 
Total$7,775 $9,317 
 
Stock-based compensation by type of award was as follows (in thousands):
 Years ended December 31,
 20242023
Stock options$4,036 $5,310 
Restricted stock units3,655 3,637 
Performance RSUs— 297 
Employee stock purchase plan84 73 
Total$7,775 $9,317 
 Employee Retirement Plan
In 2008, the Company established a retirement plan, or the Plan, authorized by Section 401(k) of the Internal Revenue Code, or IRC. In accordance with the Plan, all employees who have attained the age of 21 are eligible to participate in the Plan as of the first Entry Date, as defined, following their date of employment. Each employee can contribute a percentage of compensation up to a maximum of the statutory limits per year. Company contributions are discretionary and contributions in the amount of approximately $1.7 million were made during each of the years ended December 31, 2024 and 2023.

About Stock Compensation Disclosures

Stock-based compensation disclosures detail the equity awards granted to employees and executives — including stock options, restricted stock units (RSUs), and performance shares — along with the valuation methods and assumptions used to expense them. This section reveals the true cost of talent retention and the alignment between management incentives and shareholder interests.

Key signals: total unrecognized compensation expense and its expected recognition period signal future earnings headwinds from already-granted awards. For stock options, examine Black-Scholes assumptions — expected volatility, risk-free rate, and expected term — as understating any of these reduces reported compensation expense. Compare stock compensation expense as a percentage of revenue against peers to assess dilution cost. Watch vesting schedules for acceleration clauses tied to change-of-control events. Performance-based awards with undemanding targets may indicate weak governance. Add back stock compensation to operating cash flow to calculate a more conservative free cash flow figure.