Nobody with any capital in significant amounts is going to take this report at face value. They're going to investigate the claims on their own before they make any moves.
Roughly $7 billion in value disappeared from GE's market cap today. People are certainly going to investigate this more and the stock will move in one direction or another depending on the validity of the report, but regardless of the ultimate outcome significant capital was moved around today which presented an opportunity to make a lot of money.
The market moved too quickly for the parties acting to have had time to actually digest the merits of the report. The market moved because the people who released the report had credibility.
It's possible that that was part of it. But the market closed with GE's price barely recovering. Which means people who analyzed it more slowly agreed with the initial movement. Which means there is no evidence for the view that the initial movement was spurious or unvetted.
I think you're putting a bit too much faith in due diligence for a market that is largely run by algorithms. There was some Google traffic for "GE fraud" right before market open and then search traffic spiked at 10:40am.[1] Now look at the trajectory of GE's share price this morning.[2]
I'm really not. The price closed down quite a bit. It recovered only a little bit of its loss by the end of the day. Which means the algorithms that traded quickly are in agreement with the humans who traded slowly.