** Shares of Ascletis Pharma Inc 1672.HK fall 10.2% to HK$16.4, on track for the biggest one-day pct drop since June 17

** The pharmaceutical products developer plans to sell 28.82 million new shares to key shareholders in a top-up placement of shares, raising HK$474 million ($60.72 million) for R&D of drug candidates and working capital

** The new shares will be issued at HK$16.45 each, or a 9.9% discount to Monday's close of HK$18.26 each

** The key shareholder will buy the new shares following sales of 52.4 million existing shares at the same price to third-party investors

** Hang Seng Biotech Index .HSHKBIO falls 1.2%, benchmark Hang Seng Index .HSI slips 0.2%

** YTD, stock up 445.9%

($1 = 7.8061 Hong Kong dollars)

(Reporting by Donny Kwok)

((donny.kwok@thomsonreuters.com))