William Blair analyst Andy Hsieh is an “aggressive” buyer of Nektar Therapeutics (NKTR) on today’s selloff. The stock is down after management disclosed that the scope of collaboration with partner Bristol-Myers (BMY) is now narrowed to roughly five or six registrational trials from the planned 18 first announced in January of this year, and that there were some issues pertaining to the manufacturing of bempegaldesleukin that potentially led to the drastic difference in response rate between the November 2017 and June 2018 data announcement of the Phase II PIVOT-02 results, Hsieh tells investors in a research note. While acknowledging that the development is “directionally negative,” the analyst believes the magnitude of the Nektar selloff overshoots the potential impact. In addition, Nektar is working with the FDA and partner Bristol-Myers to resolve the manufacturing issue by establishing new quality control initiatives, Hsieh points out. He believes empegaldesleukin “remains differentiated” and he keeps an Outperform rating on Nektar Therapeutics. The stock in premarket trading is down 37%, or $10.92, to $18.65.