Whether it has other implications for the global economy as a whole is open for debate.

It's a question occupying the mind of Ivan Colhoun, NAB's Chief Economist Markets, who wrote in a note to clients this morning that:

There is likely to remain considerable discussion about just what the continuing sharp decline in oil prices means – is it a signal of much slower global economic growth or greater energy supply? Depending on the answer, we either have a significant pressure for lower interest rates or an effective tax cut for global consumers.

Whichever way the discussion goes there is a chart of the relationship between Oil prices and the S&P which should scare the heck out of global stock traders: