The landscape is littered with people shorting, and people who have claming "we're going down". To go down we need some news, over the last 10 years often bad news has driven the market up so many times.. Regularly we hit a new all time high every few days...
So I am only suggesting something has shifted, we have had two weeks of selling. Other than news what could send us down, well of course "Paper" Wall Street Insiders could send us down, Paper selling all day long, and day after day is a distant memory, but that could do it.