CNBC's Jim Cramer is confident that he's pinpointed the real cause of the market-wide sell-off that has weighed on stocks for much of the week.
"The real culprit behind today's decline is the same miscreant that's weighed us down for the last couple of days: the unspooling of these obscure products that allowed ... idiotic money managers and neophyte investors to bet against what's known as volatility," the "Mad Money" host said.
Very few stocks can withstand hedge-fun-led pain like this, Cramer warned. Big dividends don't help because the market is declining all at once, valuation is no defense because stocks can always go lower and stock buybacks only help "sop up" the shares being sold, he said.
The only stocks that really work are ones that are able to deliver drastic surprises to the upside, like Twitter after its Wednesday earnings report or GrubHub and Nvidia after their Thursday reports.
"Nvidia reported after the close and it was down hard all day today because of this nonsense I'm describing. But this stock managed to rally in the after-market because the quarter was that fantastic," Cramer said. "If we get a huge down opening tomorrow, which is certainly likely because of what I described, and Nvidia, the stock, goes lower, it might be worth buying. But if it's up big, though, you stay away. It will most likely be pulled down. Don't chase a thing in this market. That's a fool's errand."