Financial stocks have begun to underperform the S&P 500, and some say that could be a big risk to the broader market rally.
"The reality is that financials, which are the biggest part of the market in many ways, and the second-biggest weight—they don't act well," Oppenheimer's chief market technician, Carter Worth, said. The sector "has been underperforming for five months, and that's a problem."
While the S&P 500 has risen 7.6 percent in the past five months, the SPDR Financial ETF (XLF) has only risen 3.8 percent. And even as the market continues to make all-time highs, key financial stocks like JPMorgan, Bank of America and Berkshire Hathaway haven't made fresh 52-week highs since July.
So are the financials predicting a turnover for the market as a whole?