Stephen L. Mayo, Ph.D.
Merck & Co.About Stephen L. Mayo, Ph.D.
Stephen L. Mayo, Ph.D. (age 63) is an independent director of Merck & Co., Inc. (MRK), serving since 2021. He is Bren Professor of Biology and Chemistry, Merkin Institute Professor, and former Chair of the Division of Biology and Biological Engineering at Caltech; a co-founder of Xencor; former Vice Provost for Research at Caltech; and a member of the National Academy of Sciences, with prior service on the NSF National Science Board and the AAAS board. He also serves on the boards of Allogene Therapeutics, Inc. and Sarepta Therapeutics, Inc. .
Past Roles
| Organization | Role | Tenure | Committees/Impact |
|---|---|---|---|
| California Institute of Technology (Caltech) | Merkin Institute Professor | 2021–present | Senior academic leadership in science and technology |
| Caltech | Bren Professor of Biology and Chemistry | 2007–present | Scientific leadership in protein design |
| Caltech | Chair, Division of Biology and Biological Engineering | 2010–2020 | Led division strategy and operations |
| Caltech | Vice Provost for Research | 2007–2010 | Oversaw technology licensing program |
| Howard Hughes Medical Institute | Investigator | 1994–2007 | Biomedical research leadership |
External Roles
| Organization | Role | Tenure | Notes |
|---|---|---|---|
| Allogene Therapeutics, Inc. | Director | 2021–present | Current public directorship |
| Sarepta Therapeutics, Inc. | Director | 2021–present | Current public directorship |
Board Governance
- Committee assignments: Audit Committee member; Research Committee member (Research chaired by Paul B. Rothman, M.D.) .
- Independence: Listed as independent director; all standing Board committees (Audit, C&MD, Governance, Research) are comprised solely of independent directors .
- Attendance and engagement: Board met 7 times in 2023; independent directors held 6 executive sessions; all directors attended at least 75% of Board and applicable committee meetings in 2023 .
- Committee meeting cadence: In 2024, Audit (8), C&MD (5), Governance (4), Research (4) meetings were held, underscoring active oversight rhythms .
- Governance practices: Prohibition on hedging/pledging; annual majority vote standard with resignation policy; robust shareholder rights and transparency disclosures .
Fixed Compensation
| Element | Amount | Period | Notes |
|---|---|---|---|
| Annual cash retainer | $120,000 | 2024 | Program schedule |
| Audit Committee member retainer | $10,000 | 2024 | Program schedule |
| Fees earned or paid in cash (Mayo) | $130,000 | 2024 | Reported actual |
| Fees earned or paid in cash (Mayo) | $130,000 | 2023 | Reported actual |
- Ownership guidelines: Directors must attain stock ownership equal to 5× the annual cash retainer within five years; as of Dec 31, 2024, all directors serving at least three years have met or exceeded requirements .
Performance Compensation
| Element | Amount | Period | Vesting/Structure | Performance Metrics |
|---|---|---|---|---|
| Annual mandatory deferral (cash-settled DSUs) | $220,000 | 2024 | Credited to Director’s DSU account; payable in cash after service ceases (no sooner than one year) | None disclosed for director compensation |
| Annual mandatory deferral (cash-settled DSUs) | $220,000 | 2023 | Credited to Director’s DSU account | None disclosed for director compensation |
- Matching gifts: Eligible for Merck Foundation matching gifts up to $30,000 annually; multiple directors received matches in 2024/2023 (not specifically Mayo) .
Other Directorships & Interlocks
| Company | Industry | Role | Potential Interlock/Conflict Notes |
|---|---|---|---|
| Allogene Therapeutics, Inc. | Biopharma (cell therapy) | Director | Biopharma board overlap; Governance Committee annually reviews related person transactions; none required disclosure for 2023 |
| Sarepta Therapeutics, Inc. | Biopharma (genetic medicines) | Director | Biopharma board overlap; no Item 404(a) transactions disclosed for 2023 |
Related party review outcome: Governance Committee determined no transactions required disclosure under Item 404(a) for 2023 .
Expertise & Qualifications
- Scientific/technology expertise in protein design; National Academy of Sciences member; prior NSF National Science Board and AAAS board roles .
- Technology licensing experience as Caltech Vice Provost for Research; co-founder of Xencor (antibody engineering) .
- Aligns with Research Committee oversight focus on cutting-edge scientific developments and enabling technologies .
Equity Ownership
| Holder | Shares Beneficially Owned | Phantom Stock Units (DSUs) | Total | % of Shares Outstanding |
|---|---|---|---|---|
| Stephen L. Mayo | 100 | 9,581 | 9,681 | <1% (2,521,758,443 outstanding as of Mar 3, 2025) |
- Hedging/pledging: Company policy prohibits directors from hedging and pledging Company securities .
Insider Trades and Section 16 Compliance
| Item | Status | Period | Notes |
|---|---|---|---|
| Section 16(a) filings (timeliness) | No delinquent filings attributed to Mayo in 2023 | 2023 | Proxy notes two delinquencies (others), none for Mayo |
Governance Assessment
- Board effectiveness: Mayo’s deep domain expertise in protein design and R&D governance complements MRK’s Research Committee remit, reinforcing oversight quality over discovery and enabling technologies .
- Independence and alignment: Independent status, committee-only independent composition, and prohibition on hedging/pledging support investor alignment; director ownership guidelines at 5× retainer promote skin-in-the-game, with 3+ year directors meeting/exceeding targets .
- Compensation structure: Stable, modest cash retainer plus DSU deferral; no options/PSUs or performance metrics—limits pay-for-performance signaling at director level but aligns via stock-denominated deferral and ownership guidelines .
- Conflicts/related party risk: Service on biopharma boards (Allogene, Sarepta) creates potential information-flow sensitivities; Governance Committee’s annual review found no Item 404(a) transactions for 2023, mitigating immediate conflict concerns .
RED FLAGS
- None disclosed: No related-party transactions requiring disclosure for 2023; no hedging/pledging; no delinquent Section 16(a) reports attributed to Mayo .
Implications for investor confidence
- Scientific depth and active committee service strengthen R&D and compliance oversight. Director compensation and ownership policies are conservative and alignment-oriented. Cross-board roles in biopharma warrant continued monitoring, but current disclosures show no related-party issues, supporting governance quality at MRK .