** Summit Therapeutics' SMMT.O shares down 9% post-market to $13 as it seeks equity raise

** Biopharma oncology firm launches $500 mln stock offering

** Co intends to use net offering proceeds to fund R&D of its lead product candidate, lung cancer drug ivonescimab, and for working capital and general purposes.

** JP Morgan, Goldman Sachs and Citigroup joint bookrunners

** SMMT shares finished up 1.3% at $14.29 on Tues, trimming YTD loss to 18%

** Miami, Florida-based firm has ~776.2 mln shares outstanding for about $11 bln market cap

** Avg rating of 18 analysts is "buy"; median PT $32, according to LSEG data