C3.ai CEO Thomas Siebel sells 444,000 shares for $4.8M as stock slides 40% from highs

C3.ai founder and CEO Thomas Siebel offloaded 444,248 shares of his company’s stock across two days in mid-September, pocketing roughly $4.78 million in gross proceeds. The transactions landed while C3.ai’s stock was trading around $10.65, a far cry from its 52-week high of $20.22.

The shares were exercised from vested stock options with a strike price of $3.90, meaning Siebel’s actual profit, before taxes and transaction costs, came in at approximately $3.05 million.

Breaking down the trades

Siebel executed the sales over two consecutive days. On September 15, he sold 282,001 shares at a weighted-average price of roughly $10.90. The following day, he moved another 162,247 shares at an average of $10.54.

Both transactions were conducted under a Rule 10b5-1 trading plan that Siebel had established back in September 2024. These plans are essentially pre-programmed sell orders that executives set up in advance, specifically to avoid any appearance of trading on material non-public information.

After the sales, Siebel still directly holds 722,362 shares. This wasn’t an isolated event, either. Siebel has executed similar option-exercise-and-sell transactions throughout 2026, a pattern consistent with ongoing liquidity management.

The stock’s rough year in context

C3.ai’s stock has been on a bumpy ride. Over the past 52 weeks, shares have swung between $7.68 and $20.22. Trading near $10.65 at the time of Siebel’s sales puts the stock roughly in the middle of that range, but well below its peak.

The company, which builds enterprise AI software for industries like defense, energy, and financial services, rode the broader AI hype wave higher before gravity took hold.

What insider sales actually tell us

Siebel’s options carry a November 2028 expiry, so there was no immediate urgency to exercise, but the pre-established plan removes any inference about timing.

Academic research on insider trading patterns generally finds that insider purchases are a stronger signal than insider sales. Buying stock with your own money is almost always a bullish statement. Selling, by contrast, can mean almost anything.

C3.ai’s $1.7 billion market cap puts it in a precarious middle ground: large enough to attract institutional scrutiny, but small enough that a few bad quarters could meaningfully reshape the investor base.

Disclosure: This article was edited by Diego Almada Lopez. For more information on how we create and review content, see our Editorial Policy.