Every corporate insider has a problem the rest of us don't: they almost always know something. The order book, the pipeline, the deal about to close or quietly die. So the moment an executive tries to sell a few shares to buy a house, they're standing on a legal landmine — sell while you know something material, and a routine transaction starts to look like insider trading.
Rule 10b5-1 is the defuser. Adopted in 2000, it lets an insider write down a plan in advance — how many shares, at what price or on what dates, run by a broker on autopilot — while they're in an open window and genuinely know nothing market-moving. Once the plan is set, the trades execute on their own. The insider gets a "safe harbor": a prearranged, hands-off sale can't be insider trading, because the decision was made before they knew anything.
It's a sensible rule. It's also the single biggest source of false signals in the entire market.
Selling means a hundred things
People sell stock for reasons that have nothing to do with the company. A tax bill. A divorce. A second home. A financial advisor nagging them to diversify out of a position that's become 90% of their net worth. And, more than any of these, because a plan they signed eighteen months ago told their broker to.
That's why a scheduled sale is the loudest-looking, emptiest line in a Form 4. The headline writes itself — "CEO SELLS $40M IN STOCK" — but the executive may not have touched a button or formed a fresh opinion. The calendar did the selling. Reacting to it is reacting to noise wearing a suit.
The founder on autopilot
Watch a company long enough and you'll see the pattern: a founder or long-tenured executive with a standing 10b5-1 that trims a steady ribbon of shares every quarter, in good markets and bad. Bobby Murphy, Snap's co-founder and chief technologist, has parted with a great deal of stock over the years — much of it the prearranged, drip-feed kind that a plan set in advance keeps executing regardless of where the price goes.
Read literally, a relentless schedule of selling isn't a thundering vote of no-confidence — it's a personal finance decision, often just turning paper wealth into cash. But it isn't a vote of confidence either. A plan that sells the same slug of shares whether the stock is at $8 or $80 is, by design, an opinion-free transaction. The one thing it cannot be is a fresh bet that the company is cheap.
You can schedule a sale. You cannot schedule conviction.
What the schedule can't fake
Now flip it. An open-market purchase — personal money, at the prevailing price, not a granted option, not a plan — has no safe harbor and no autopilot. The insider had to decide, today, that the stock is worth more than the market is asking, and sign their name to it within two business days. Nobody buys their own shares to pay a tax bill. And when three insiders do it inside eleven days — the cluster — you're watching the people who know the value disagree, in public, with the man quoting the price.
The SEC has spent the last few years making 10b5-1 harder to abuse — mandatory cooling-off periods before the first trade, certifications that the insider knew nothing when they adopted the plan, and far more disclosure about when plans start and stop. Useful guardrails. But they don't change the core truth: a prearranged sale tells you about someone's calendar, not their conviction.
Which is the entire job. Most of what looks like a signal is a 10b5-1 schedule, and the work is throwing it out — filtering the noise so the rare, deliberate, on-the-record buy can actually be heard. AlphaSignal reads every Form 4 the moment it lands, strips out the scheduled selling, and scores what's left: not who sold on autopilot, but who chose to buy.