Citi analyst Joel Beatty downgraded Dimension Therapeutics (DMTX) to Sell saying his base case is now the takeover proposed by Ultragenyx (RARE) will go ahead. Since Dimension s currently trading at a small premium to the $5.50 per share proposal, the analyst downgraded the stock to Sell. Beatty sees a "small but real potential" for a higher bid to come in. He believes, however, that a successful bid from Regenxbio (RGNX) would likely need to be double its original offer. The analyst raised his price target for Dimension shares to $5.50 from $3.41.