Can CEOs make market moving "bluffs"? Sounds like another word for securities fraud.

(what isn't)

Of course they can, but they can't do these and sell/buy stocks involved at the same time. It's not illegal to influence stocks value (one could argue just being a CEO does that), but buying/selling while in possession of insider knowledge.

Let's say Sam called his broker and said to him on Friday we'll before the market closes. Buy MSFT stock. Then he made his announcement on Sunday and on Monday he told his broker to sell that stock before he announced he's actually coming back to (not at all)OpenAI. That would be illegal insider trading.

If he never calls his broker/his friends/his mom to buy/sell stock there's nothing illegal.

Securities fraud is more than insider trading. Misleading investors about a company’s financial health is fraud 101 and it sure looks like he lied about hiring someone to stem a precipitate MSFT drop.

Or, it did seem like a deal, but all of OAI did align that that to be more disastrous than whatever apocalypse that Altman as the CEO must entail.

Also to lessen the MSFT share impact.