The "Fast Money" traders staked out positions in the market Thursday after the worst day of 2013 for stocks.
"You may start to see people looking to sell rallies," Dan Nathan of RiskReversal.com said, who also noted that volatility has ruled recently.
Nathan also said that technicals are more important in such a market, with the S&P 500 bouncing off its resistance four times this year.
Now, with the index closing at 1,588.19, down 2.5 percent, Nathan said that investors should keep an eye on 1,600.
"It's a massive resistance level now," he said. "I think you sell these rallies."