Charts say market headed lower. What to sell

NYSE New York Stock Exchange traders markets
Brendan McDermid | Reuters

Technical analysts, those who study charts to make buying and selling decisions, believe a bigger pullback could begin this week.

Among the patterns worrying the analysts are a series of "lower highs" by the S&P 500, the underperformance of key sectors such as biotech and transports, and the outperformance by bonds.

"Tactically we see downside risk on SPX to the 200 DMA (daily moving average) at 2,013. While there is near-term support at 2,040, given the lack of short-term oversold conditions and Friday's negative reaction in the futures, we think 2,040 is unlikely to hold," wrote Jonathan Krinsky, chief market technician at MKM Partners, in a note to clients Sunday.