NEW YORK (TheStreet) -- The quarter is ending and stocks are lower Tuesday. Some sectors are continuing to show strength including health care, said Pete Najarian, co-founder of optionmonster.com and trademonster.com, during CNBC's "Fast Money Halftime." But Najarian is looking to play defense, not offense and thinks investors should buy portfolio protection as long as volatility -- as seen by the CBOE Volatility Index -- remains low.