Every fact below links to its source. Informational only. Ownership statements are limited to primary announcements and filings.
- Headquarters
- San Jose, CaliforniaSource: markthomas.com/who-we-are
- Ownership type
- Employee-owned (ESOP and common stock): Employee Owned page states 100% employee-owned since inception, with shares in an ESOP and individual common stock shareholdersSource: markthomas.com/employee-owned
- Sponsor or parent
- Firm Employee Owned page: ESOP plus common stock shareholders; DOL Form 5500 lists Mark Thomas & Company, Inc. Employee Stock Ownership Plan (NAICS 237310)Source: markthomas.com/employee-owned
- Website
- markthomas.comSource: markthomas.com/who-we-are
Legal name, DBA and former names
- Mark Thomas & Company, Inc. (Mark Thomas)Source: markthomas.com/who-we-are
Identifiers (UEI, state registrations)
- ENR 2026 Top 500 Design Firms list entry Mark Thomas, San Jose, Calif.Source: enr.com/toplists/2026-top-500-design-fi…
Ownership type
- Employee-owned (ESOP and common stock): Employee Owned page states 100% employee-owned since inception, with shares in an ESOP and individual common stock shareholders.Source: markthomas.com/employee-owned
Sponsor, parent or transaction
- Firm Employee Owned page: ESOP plus common stock shareholders; DOL Form 5500 lists Mark Thomas & Company, Inc. Employee Stock Ownership Plan (NAICS 237310)Source: markthomas.com/employee-owned
Services and markets
- Civil engineering, construction management, surveying, landscape architecture, planning and structures engineering focused on mobility and community infrastructure.Source: markthomas.com/who-we-are
Leaders
- Zach Siviglia, PE, QSD, President and Chief Executive Officer.Source: markthomas.com/who-we-are/leadership-team
- Chad Caldwell, PE, Chief Operating Officer.Source: markthomas.com/who-we-are/leadership-team
- Kimberly Post, CPA, Chief Financial Officer and Associate.Source: markthomas.com/who-we-are/leadership-team
ESOP plan data (Form 5500)
- DOL Form 5500 plan year beginning 2024: MARK THOMAS & COMPANY, INC. EMPLOYEE STOCK OWNERSHIP PLAN (ACK_ID 20251009142835NAL0007136241001), 376 active participants, NAICS 237310.Source: dol.gov/agencies/ebsa/about-ebsa/our-ac…
Public filings
- DOL Form 5500 plan year beginning 2024, NAICS 541330: MARK THOMAS & COMPANY, INC. 401(K) SAVINGS PLAN (ACK_ID 20251003162901NAL0001612257001, 407 active participants)Source: dol.gov/agencies/ebsa/about-ebsa/our-ac…
Rankings and awards
- Listed in the ENR 2026 Top 500 Design Firms.Source: enr.com/toplists/2026-top-500-design-fi…
News timeline
- Firm Employee Owned page states Mark Thomas remains committed to remaining employee-owned and contrasts PE buyouts in the A/E industry.Source: markthomas.com/employee-owned
Sources of record
Ownership tag: Employee-owned (ESOP). Profiles are informational, compiled from public sources linked above. Firms may request corrections. A listing is not an endorsement.
