Michael J. Petro was named Chief Financial Officer of Martin Marietta Materials Inc. As of November 6, 2026, Martin Marietta Materials Inc has reported 3 leadership change filings to the SEC under Item 5.02 of Form 8-K, from April 27, 2026 to August 24, 2026, naming 3 appointments (Form 8-K, August 4, 2026).
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Key facts
- · In / out: In · Person: Philipp Niemann · Role: Director · Effective: 2026-08-21 · 8-K, 2026-08-24
- · In / out: In · Person: Michael J. Petro · Role: Chief Financial Officer · 8-K, 2026-08-04
- · In / out: In · Person: Christopher W. Samborski · Role: Chief Operating Officer · Effective: 2026-05-01 · 8-K, 2026-04-27
Martin Marietta Materials Inc reported changes in 3 filings among its directors and officers to the SEC on Form 8-K, Item 5.02, from 2026-04-27 to 2026-08-24. They name 3 people. Every row below is cited to the filing it comes from, and this page adds each new change as Martin Marietta Materials Inc files it.
Also on the record for Martin Marietta Materials Inc
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| October 30, 2026 | Stake report, Schedule 13G/A, by Vanguard Capital Management | 6.41% of the class | 5%+ stakes | Source |
| October 30, 2026 | Stake report, Schedule 13G/A, by Vanguard Portfolio Management | 4.65% of the class | 5%+ stakes | Source |
| August 24, 2026 | Stake report, Schedule 13D, by LNA Holding SRL | 15.4% of the class | 5%+ stakes | Source |
| August 21, 2026 | Acquired Lhoist North America, Inc. | $7B | Acquisition | Source |
| August 7, 2026 | Stake report, Schedule 13G, by STATE STREET CORPORATION | 5.2% of the class | 5%+ stakes | Source |
| April 30, 2026 | Stake report, Schedule 13G, by Vanguard Capital Management | 7.47% of the class | 5%+ stakes | Source |
| April 29, 2026 | Stake report, Schedule 13G, by Vanguard Portfolio Management | 5.25% of the class | 5%+ stakes | Source |
| March 27, 2026 | Stake report, Schedule 13G/A, by The Vanguard Group | — | 5%+ stakes | Source |
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More on Martin Marietta Materials Inc and the records around it.
Martin Marietta Materials Inc elsewhere on the record
- 5%+ stake filings Oct 2026
- Acquisition Aug 2026
- Who owns it
Companies that share a holder
- STATE STREET CORPORATION also filed stake reports on 343 other companies: TRADE DESK INC/THE (Oct 2026), CENTRUS ENERGY CORP (Sep 2026), ACADIA PHARMACEUTICALS INC (Aug 2026)
- Vanguard Portfolio Management also filed stake reports on 941 other companies: Newmark Group Inc (Nov 2026), A10 Networks Inc (Oct 2026), ADT Inc (Oct 2026)
- Vanguard Capital Management also filed stake reports on 1495 other companies: A10 Networks Inc (Oct 2026), Altisource Portfolio Solutions SA (Oct 2026), Alto Neuroscience Inc (Oct 2026)
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Timeline
| Filed | In / out | Person | Role | Effective | Source |
|---|---|---|---|---|---|
| 2026-08-24 | In | Director | 2026-08-21 | 8-K, 2026-08-24 | |
| 2026-08-04 | In | Chief Financial Officer | 8-K, 2026-08-04 | ||
| 2026-04-27 | In | Chief Operating Officer | 2026-05-01 | 8-K, 2026-04-27 |
Who leads Martin Marietta Materials Inc, as last reported?
For each role that changed in the filings below, the most recent change reported. A role that did not change in these filings is not listed.
- Director: Philipp Niemann, appointed, effective 2026-08-21 (filed 2026-08-24).
- Chief Financial Officer: Michael J. Petro, appointed (filed 2026-08-04).
- Chief Operating Officer: Christopher W. Samborski, appointed, effective 2026-05-01 (filed 2026-04-27).
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Appointed: Philipp Niemann, Director, effective 2026-08-21
Pursuant to the Shareholders Agreement, on August 21, 2026, the Board increased its size from ten to eleven directors and appointed Mr. Philipp Niemann, effective as of August 21, 2026, to fill the newly-created directorship.
- Mr. Niemann will serve until Martin Marietta's 2027 Annual Meeting of Shareholders.
- Mr. Niemann will serve on the Finance Committee of the Board.
- Mr. Niemann currently serves as the Chief Executive Officer of Lhoist S.A. ("Lhoist").
- From April 2022 to October 2025, Mr. Niemann served as President and Chief Executive Officer of LNA and as a member of Lhoist Executive Committee.
- Prior to April 2022, Mr. Niemann held several other positions at Lhoist, which he joined in 2013.
- Mr. Niemann will participate in Martin Marietta's non-employee director compensation program, which currently provides all non-employee directors with an annual cash retainer of $135,000 and an annual award of restricted stock units with a grant date value of $180,000.
- Mr. Niemann's first award of restricted stock units under the non-employee director compensation program was effective upon his appointment to the Board.
- The terms and conditions of the award of restricted stock units, as well as the other terms and conditions of the non-employee director compensation program, are consistent with those described in Martin Marietta's proxy statement for its 2026 annual meeting of shareholders.
Appointed: Michael J. Petro, Chief Financial Officer
On August 4, 2026, Martin Marietta Materials, Inc. (the "Company") announced that the Company has promoted Michael J. Petro to Executive Vice President, Chief Financial Officer.
- In connection with his promotion to the role of Executive Vice President, Chief Financial Officer, the Company and Mr. Petro executed an employment agreement (the "Employment Agreement") and an amended and restated employment protection agreement (the "Employment Protection Agreement").
- The Employment Agreement provides that in the event of a termination by the Company without cause or by Mr. Petro for good reason, Mr. Petro is entitled to a severance amount equal to three times the sum of his base salary and target bonus, continued medical and dental benefits for up to three years, and continued vesting of his outstanding equity awards.
- The Employment Agreement includes a three-year post-termination, non-competition, non-solicitation, and confidentiality covenant.
- The Employment Protection Agreement, which aligns with the Company's Employment Protection Agreements provided to other executive officers, provides for severance benefits upon a qualifying termination following a change of control of the Company equal to three times Mr. Petro's annual compensation (defined as base salary and the highest annual bonus paid in the preceding five years) and continuation of benefits for 36 months.
Appointed: Christopher W. Samborski, Chief Operating Officer, effective 2026-05-01
On April 27, 2026, Martin Marietta Materials, Inc. (the "Company") announced that the Company has appointed Christopher W. Samborski, to serve as the Company's Executive Vice President and Chief Operating Officer, effective as of May 1, 2026 (the "Effective Date").
- Mr. Samborski, age 45, joined the Company in August 2018 and currently serves as President of the West and Specialties Divisions.
- In January 2025, he assumed the leadership of the West Division and retained his responsibilities as President of Specialties which he has led since January 2022.
- Mr. Samborski served as Vice President of Strategic Finance, Procurement and Supply Chain beginning in January 2020 prior to his current roles and served as Vice President of Strategic Finance from 2018 to 2020.
- Prior to joining the Company, Mr. Samborski spent close to ten years in leadership roles at Caterpillar Inc. and Johnson & Johnson.
- Mr. Samborski began his career with General Electric Company and was selected for and completed GE's elite Operations Management Leadership Program.
- Mr. Samborski holds a Bachelor of Science degree in industrial engineering from the University of Wisconsin-Madison and an MBA in strategy and general management from the University of Michigan's Ross School of Business, where he received the Ross Distinguished Scholar Award and graduated with high distinction.
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Where this comes from
A public company must file a current report on Form 8-K with the SEC within four business days when a director leaves or is elected, or when its chief executive, chief financial, chief accounting or chief operating officer, or another named executive, departs or is appointed. That disclosure goes under Item 5.02 of the report.
Every change on this page is taken from one of those filings and quoted in the company's own words, with a link to the filing, so it can be checked at the source. Where a filing names the person, the role and the date a change takes effect, they are shown beside the quote. Where it does not, the quote stands on its own. A filing states what changed; it rarely states why, and neither does this page.