Which came first: low oil prices or declining stocks?

The price of oil went down Monday and the S&P 500 stock index finished down 1.6 percent. Early Tuesday morning, the price of oil firmed up and stock index futures also went from down to up. Conventional wisdom pointed to oil as the cause of Monday’s declines, the argument being that oil is a crucial indicator of the global economy. But are stocks low because of lower oil prices or vice versa?

Click the player above for a discussion of the high correlation between the prices of stocks and oil, as well as what’s driving it.