** Shares of Australian pharmacy chain operator Sigma Healthcare SIG.AX rise 10.2% to A$2.975, its highest level since Jan. 14

** SIG biggest gainer in the ASX200 benchmark index .AXJO

** Merger partner Chemist Warehouse reported 13% growth in retail network sales over 1H25, with like-for-like sales growing at a record 10.3%

** Citi says (Chemist) result suggests combined group is tracking well ahead of expectations

** SIG shareholders will vote on the merger with Chemist on Jan. 29

** More than 8.6 mln SIG shares change hands, 1.2 times the 30-day average of 6.9 mln shares

** SIG up 13.7% so far this year, including the day's moves, extending its 161% gain clocked in 2024

($1 = 1.5954 Australian dollars)

(Reporting by Sameer Manekar in Bengaluru)

((Sameer.Manekar@thomsonreuters.com;))