** Regenxbio's RGNX.O shares down 14.1% to $9.62 post-market as it plans equity raise

** Rockville, Maryland-based biotech firm announces $100 mln stock offering

** Morgan Stanley, JP Morgan, Leerink and Mizuho joint bookrunners

** RGNX intends to use net offering proceeds for general purposes, including financing clinical trials, capex, working capital, development of product candidate pipeline, pay down debt, among other purposes, per the prospectus

** Last month, RGNX said U.S. FDA reversed rejection of co's rare-disease gene therapy, Navsunli, backs accelerated approval bid, and co said to receive $100 mln milestone payment from partner AbbVie ABBV.N for its eye disease drug

** RGNX shares finished down 8.7% at $11.20 on Thurs. Stock has rallied 62% over the past month, leaving it down 22% YTD

** Co has roughly $580 mln market cap