Thomas Siebel vs Mark Zuckerberg
Real-time net worth, career, and company comparison — updated May 2026.
Wealth at a Glance
Net worth gap: $203.7B — equivalent to 98% of Mark's total wealth.
Tale of the Tape
Net Worth History
| Year | Thomas | Mark | Leader |
|---|---|---|---|
| 2022 | — | $65B | — |
| 2023 | — | $170B | — |
| 2024 | $3.9B | $224.1B | Mark |
| 2025 | $3.9B | $222B | Mark |
| 2026 | $3.956B | $207.68B | Mark |
Career Highlights
Thomas Siebel
- 1984Joined OracleHeld various management positions at Oracle Corporation.
- 1993Founded Siebel SystemsFounded Siebel Systems, a CRM software company.
- 2006Siebel Systems AcquiredSiebel Systems was acquired by Oracle for $5.8 billion.
- 2009Founded C3.aiFounded C3.ai, an enterprise AI software company.
- 2025Transitioned to Executive ChairmanTransitioned to Executive Chairman of C3.ai.
Mark Zuckerberg
- 2004Founded FacebookCo-founded Facebook while at Harvard University.
- 2008Became a BillionaireBecame a billionaire at age 23.
- 2012Facebook IPOTook Facebook public, making it one of the largest IPOs in history.
- 2021Meta RebrandingFacebook rebranded to Meta Platforms, Inc., focusing on the metaverse.
The Verdict: Mark Zuckerberg vs Thomas Siebel
As of May 2026, Mark Zuckerberg leads this comparison with a net worth of $207.68B, placing at #6 in the global rankings. Thomas Siebel follows at $3.956B — a gap of $203.7B.
Both executives operate in the Technology sector, making this a direct peer comparison. Their wealth trajectories reflect the broader performance of that industry over time, though individual company strategy, equity ownership structure, and capital allocation decisions have driven meaningfully different outcomes.
Thomas Siebel is 73 years old versus 41 for Mark Zuckerberg, a difference of 32 years. Age context matters in wealth comparisons: a younger billionaire at the same net worth has had less time to accumulate — and in many cases represents a higher compound annual growth rate on their wealth.
Net worth figures are estimates calculated from public shareholding disclosures, stock price data, and reported asset values. See our full methodology.
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Net worth estimates updated daily from public financial disclosures. Methodology · Report an error