The market had a real "nasty feel" to it Monday, but any move lower could still be a buying opportunity for the long-term investor, trader Ben Willis said.
"I'm still bullish. I don't think this is the final song by any means," the managing director for Princeton Securities said in an interview with CNBC's "Closing Bell" on Monday.
This week's Federal Reserve meeting and the upcoming U.K. vote on whether it will leave the European Union weighed on investors Monday, with the Dow Jones industrial average closed down about 132 points.
The CBOE Volatility Index (VIX), widely considered the best gauge of fear in the market, spiked above 21 for the first time since Feb. 25.