Are 10b5-1 sales less informative than open-market sales?

Generally, yes.

A sale made under a Rule 10b5-1 plan is usually seen as less informative than an unscheduled discretionary open-market sale because the plan is intended to be adopted in advance, when the insider is not aware of material nonpublic information, and the trade is then executed according to predetermined terms.

That said, a 10b5-1 sale should not be treated as meaningless. It can still matter if: - the plan was adopted recently - the trade is unusually large - sales recur in a consistent pattern - multiple insiders are selling - other context suggests the transaction is important

So the best approach is to treat 10b5-1 sales as generally weaker signals, but still evaluate size, timing, and pattern.