Oppenheimer analyst Leland Gershell upgraded Amarin (AMRN) to Perform from Underperform and removed his $12 price target, given the sharp decline expected in the stock this morning.

The shares are indicated to open at $4.10 in pre-market trading, which would be a 70% decline from yesterday's close, following Judge Miranda Du's ruling that Vascepa's patent claims are invalid. While the company intends to appeal, the ruling significantly reduces expectations around the product's market exclusivity period and Gershell puts generic launches in 2022-23 as a "best case," adding that at-risk launches could occur much sooner, pending ANDA approvals.

Vascepa's "heavily-truncated exclusivity" meaningfully impairs Amarin's cash flow generation opportunity and "effectively removes" the company's appeal to a prospective acquirer, added Gershell, who sees the stock trading in line with the market from here.