Key points
- Every time a corporate insider (an executive, director, or anyone who owns 10% or more) buys or sells their own company's stock, they must disclose it to the SEC within two business days, on a form called a Form 4.
- Most insider selling isn't a signal at all. A big share of it happens on a pre-scheduled plan set up months earlier, often for taxes or diversifying, not a comment on the company.
- A real example: Palantir's (PLTR) Chief Technology Officer sold 185,000 shares combined (his own and a family trust's) on July 2, 2026, all under a trading plan he set up back in March.
- Open-market buying with an executive's own cash, like S&P Global's (SPGI) CEO putting in $1 million in April, is rarer and generally taken more seriously than a scheduled sale.
Reading Form 4 filings is one of my favorite habits. They're one of the few places where you get to watch what a company's own leadership does with their own money, out in public, within days of it happening. Most people never look at one. That's their loss, honestly. A Form 4 is short, and once you know the two or three things that actually matter, it takes about thirty seconds to read.
What a Form 4 actually is
US securities law requires corporate insiders (officers, directors, and anyone who owns 10% or more of the company) to report almost every trade in their own company's stock. The form is called a Form 4, and the deadline is tight: two business days after the trade. Compare that to the 13F filings hedge funds use to disclose what they own, which can lag up to 45 days. A Form 4 is about as close to real time as SEC disclosure gets.
Two details on the form matter more than anything else. The first is the transaction code: "P" means the insider paid cash for shares on the open market, the same way anyone else would. "S" means they sold. The second is a checkbox for Rule 10b5-1. That's a legal plan an insider can set up in advance, sometimes months ahead of time, to schedule future trades automatically. The point is to let executives sell some of their stock, since they're often paid partly in shares, without anyone accusing them of trading on information they only just learned. The plan was locked in before that information even existed.
A real one from this week
Palantir Technologies' (PLTR) Chief Technology Officer, Shyam Sankar, filed a Form 4 on July 7, 2026, for a trade dated July 2. Between himself and a family trust, 185,000 shares were sold at $130 each. The box for Rule 10b5-1 is checked, and the filing spells out why: the plan was entered into on March 11, 2026, almost four months before the sale it covers.
That timing is the whole story. Sankar didn't wake up on July 2 and decide to sell. He (or whoever manages the trust) locked in a plan back in March, long before anyone could know what Palantir's stock would be doing in July. A sale like this tells you basically nothing about how the CTO feels about the company right now.
Compare that to S&P Global's (SPGI) CEO Martina Cheung. She bought about $1 million of her own company's stock on the open market in April, coded "P," with no pre-scheduled plan involved. That's rarer, and it's generally read as a stronger signal, since nothing forces an insider to spend their own cash on shares they didn't have to buy.
Quick check: does this trade actually mean something?
Here are three real situations. Click each one to see how I'd think through it.
A company's CFO sells $200,000 of stock the same week the company announces plans to repurchase its own shares.
Check the transaction code and the 10b5-1 box first. If it's marked as a pre-scheduled plan, the timing is a coincidence. Plans like this are usually set up long before anyone knows what week a repurchase announcement will land. If it isn't marked as scheduled, the timing is worth a second look. Even so, plenty of CFOs sell stock for ordinary reasons like taxes or buying a house, so one unscheduled sale still isn't proof of anything by itself.
Three different board members each buy shares of the same company, with their own cash, in the same week, none of it on a pre-scheduled plan.
This is the more interesting case. One person's routine, scheduled sale explains itself. Three separate people independently choosing to spend their own money buying the same stock in the same short window is harder to wave off, since each of them made that call on their own.
A founder who owns 40 million shares sells 5,000 of them.
Context matters here more than the transaction code. 5,000 shares out of 40 million is a rounding error, not a change in how much of the company that founder still owns. Small sales like this from someone with a massive stake usually just mean they wanted some cash, not that they've lost confidence.
Where to actually look these up
You don't need to hunt through the SEC's own site to find these. Our filings feed pulls every disclosure for the companies we track, and the "Insider (3/4/5)" filter narrows it down to exactly this kind of filing. Pick a company, click the filter, and you'll see every reported trade, along with a link to the actual filing so you can check the transaction code and the 10b5-1 box yourself.
This is general information about how SEC disclosures work, not investment advice, and none of the trades described above are a recommendation to buy or sell anything.
