Most insider trades today are not what they look like. The bulk of insider sales are 10b5-1 plan insider sales: pre-scheduled, adopted months in advance, and legally required to run on autopilot. A CEO selling under a 10b5-1 tells you about as much as a calendar reminder.
The signal lives in the exceptions. Open-market buys coded P on Form 4, where the insider chose the timing and spent cash. Discretionary sales outside a plan are rarer and worth a second look, especially when several insiders sell together with no plan on file.
A good daily routine: filter today's filings for buys only, sort by dollar value, and ignore everything tagged as plan sales. Check the footnotes too, because that is where 10b5-1 adoption actually gets disclosed.
The footnotes are where the truth hides. Form 4 footnotes disclose whether a sale was made under a 10b5-1 plan and when the plan was adopted. A plan adopted two years ago running on schedule is meaningless. A plan adopted three weeks before the sale deserves a raised eyebrow, even if it is technically compliant.
Most sales are plumbing. The buys are the story.