Biotech stocks have had an impressive run over the past year due to increased M&A and IPO activity and exciting regulatory approvals. Jim Cramer, Portfolio Manager of Action Alerts PLUS tells, the TheStreet's Jill Malandrino that he is getting more cautious on the space and gains should be preserved, although he still likes the 'Four Horsemen' mentioned in his book 'Get Rich Carefully'; Regeneron, Biogen, Celgene and Gilead. But, there are times when not to buy and hedging gains is prudent. Malandrino points out a potential hedging vehicle is the ProShares Ultrashort Biotech ETF (BIS), which has seen a pick up in volume since hitting its 52-week low.