Citi analyst Yigal Nochomovitz says shares of Portola Pharmaceuticals are down 50% since the Q2 earnings call on a "very disappointing" launch for Bevyxxa. The stock is now heavily levered to a successful launch of Andexxa, the analyst tells investors in a research note. With the stock now at $20, now is the time to re-articulate the Andexxa bull case, a lifesaving emergency therapy, says Nochomovitz. He believes Andexxa can be a $1B drug in the U.S., which he estimates is worth $42 per share alone. The analyst keeps a Buy rating on Portola Pharmaceuticals while trimming his price target for the shares to $49 from $50.