Insider trading
Look at it this way.
If I know a new wonder product is going to be launched and when, I then buy shares in the company and leak the announcement early. Shares bounce up in price based on the leak, I sell for a nice profit.
Pretty sure that is called insider trading and is certainly not free speech.
Likewise if you are in possession of bad news then you can short the shares to make a profit.
Anything else leaking can be covered by a NDA which most companies will make employees sign.
Biting the hand that feeds IT
