** Shares of Dyne Therapeutics DYN.O down 9.5% premarket on Weds to $21.56 after overnight follow-on priced

** Neuromuscular disease-focused DYN late Tues sold 18.3 mln shares at $20.50 for approx $375.15 mln gross proceeds

** Offering size increased from $300 mln and priced at 14% discount to stock's last close

** Morgan Stanley, Jefferies and Evercore joint bookrunners, along with LifeSci Capital and Raymond James

** Waltham, Massachusetts-based DYN, which has ~165.3 mln shares outstanding, expects to use net proceeds to advance its drug candidate zeleciment rostudirsen for treatment of Duchenne muscular dystrophy (DMD) and zeleciment basivarsen for myotonic dystrophy type 1 (DM1), per the prospectus

** Through Tues, DYN shares up ~22% YTD

** 15 of 16 analysts rate the stock "strong buy" or "buy", 1 "hold"; median PT $40, per LSEG data