Citi analyst Robyn Karnauskas last night downgraded Juno Therapeutics (JUNO) to Neutral from Buy while raising her price target for the shares to $81 from $59.

Juno closed yesterday up 52%, or $23.65, to $69.25 after the Wall Street Journal reported that Celgene (CELG) is in talks to acquire the company. When the story broke, Karnauskas said in a research note that Juno could be worth $110 per share in a takeover. She believes, however, that for Celgene, a deal makes sense in the $80-$85 per share range.

The analyst expects Juno to trade with an M&A premium at $81 per share. With the recent 49% jump in shares, and the stock now trading within 17% of our takeover price, Karnauskas tells investors in a research note.