Perhaps the biggest financial story of 2015 has been the continued collapse of oil prices, which has been a noticeable drag on the stock market. And some argue that the oil market will continue to drive stock movements in the year ahead.
"Oil is the meat of the volatility sandwich here, and I don't think that changes," Max Wolff of Manhattan Venture Partners said Wednesday on CNBC's "Trading Nation."
"I think the first half of 2016 is sort of a heavy-duty repeat of the second half of 2015 on the vol side," Wolff continued, "although I do think you start to see a bottom in and a rebuild going into the second half of 2016."
For Societe Generale macro strategist Larry McDonald, "the consistent relationship between lower oil prices and higher U.S. equity market volatility" has been "the story of 2015."
Any rally in equities is "suspect" without "a follow-through in oil," said McDonald. "So if oil doesn't follow equities higher and rolls over, get long volatility and short the ."
Over the past year, the CBOE Volatility Index (which uses options prices to measure expected volatility) has indeed enjoyed a daily correlation of -0.24 with oil, which indicates that a fall in oil should tend to lead to a rise in expected volatility, and vice versa.
However, that does not appear to be too far out of line with five-year and 10-year averages for the correlation between oil and the volatility index. And in fact, the relationship between oil and the S&P 500 itself is a bit tighter.
Over the past five years, the daily moves in oil and in the S&P 500 have experienced a correlation of 0.35. Correlations are measured on a scale from -1 to 1, with 0 indicating no relationship and 1 indicating perfect correlation.