8. Achillion Pharmaceuticals ( ACHN) shares spiked last month after the company said Phase 1b clinical trial data showed its ACH-1625 treatment in third and fourth patient cohorts achieved "meaningful reductions in HCV RNA after five-day monotherapy, with continued safety and tolerability in patients with hepatitis C." The stock is down more than 11% over the last month, but has nearly doubled in price over the last year. Consensus: Of the analysts covering Achillion, seven, or 77.8%, recommend purchasing its shares and two recommend holding them. Closing Price: $2.33 (June 2) Bullish Case: Roth Capital Partners has a buy rating and $12 price target on Achillion, which calls for quite a bit of upside based on current levels. "Achillion's strong clinical performance with ACH-1625 to-date, we believe should be of strong interest to investors looking to be involved in the Hepatitis C virus (HCV) space. We believe the drug's profile to-date make it a very attractive partnering candidate," the firm wrote in a research note late last month. Bearish Scenario: JMP Securities, which has a market perform rating on Achillion, argues that while the company's protease inhibitor looks good so far and suggests potential for once daily dosing, more safety data is needed. "Given how crowded the HCV protease inhibitor class is, combined with the move toward oral combination therapy, we think safety is what will ultimately differentiate these compounds," the firm said.