** CStone Pharmaceuticals 2616.HK slides 13% to HK$3, lowest since February 25

** Stock set for biggest one-day pct decline since March 7, 2024; top pct loser on Hong Kong bourse

** Chinese biopharma developer plans to sell 80 mln new shares to third party investors to raise HK$234.6 mln ($30.2 mln) for R&D and general corporate purposes

** Says shares will be issued at HK$2.933, representing ~15% discount to Tuesday's close of HK$3.45

** Stock gains 30.4% YTD

($1 = HK$7.7808)

(Reporting by Donny Kwok)

((donny.kwok@thomsonreuters.com))