If it's news on a major website, it's priced in. So yes, we know it is priced in.
Obviously, it wasn't news 5 years ago, so no it wasn't then.
There is a gray area which is where professional investors who have an informational advantage make their money. But by the time something is mainstream news, that gray area is long gone.
CEG jumping 20% on the MSFT deal means it isn’t all priced in imo. Everyone has known there are rising energy needs and had bid up CEG. Then the Three Mile Island restart news hit and apparently it wasn’t already priced in
