All-In Insider Buys: When Executives Double Their Stake

Size against the insider, not against the market

Most insider-trading lists sort purchases by dollar amount. That favors the richest buyers. A better measure of conviction is how much a purchase adds to what the insider already held. Every Form 4 reports the shares the insider owns after the trade, so we can work out the holding before it and the percentage added. An executive who goes from 20,000 shares to 50,000 has bet heavily on the company, even if the dollar amount looks small next to a fund's purchase.

Did conviction pay?

Yes and no. Three months after the purchase, buys that at least doubled the insider's holding finished a median −3.2% against the S&P 500 (across 171 purchases), compared with −1.9% for small top-ups of less than 5% (1,226 purchases). The big bets did worse, which is a useful warning: conviction is not the same as being right, and doubled stakes are often small, volatile companies.

Three months after each purchase, all purchases in our records with prices on both ends. "First shares" are purchases by someone with no earlier holding of that class, often a new director.

Biggest all-in buys of the last year

How to read it

The holding is the one reported on the same line of the Form 4: shares held directly, or through the trust or family member named. An insider may own more in other accounts, so "doubled" means doubled in that account. Options and restricted stock do not count. Purchases where the filing gives no holding are left out.

Examples

From the data: Matthew Wilks bought $34.3M of FLOTEK INDUSTRIES INC/CN/ (FTK) on Sep 11, 2026, raising the holding in that account by 836%. You can see the Form 4 on SEC EDGAR.

A worked example: a director owns 10,000 shares at $30 ($300,000). She buys 10,000 more for $300,000. In dollars that is a modest trade; for her it doubles her exposure to the company. A chief executive who owns 5 million shares and buys 10,000 has spent the same money but added 0.2%.

Explain it like I'm 13

If your friend with $10 of pocket money spends $10 on a card, that tells you more about how much he likes the card than if a kid with $1,000 spends the same $10. This page looks at how much of their own pile each insider put in, not just the price tag.

Built from SEC Form 4 and 13F filings and STOCK Act reports as read by WallStPal, rebuilt every day. Prices are weekly closing prices derived from SEC data and can lag by a few weeks. Results describe what stocks did, not anyone's profit, and are not investment advice. See our method.