** HK shares of Bilibili 9626.HK falls 5.8% to HK$198.4, lowest since January 2

** Stock on track for biggest one-day pct drop since January 19; top pct loser on Hang Seng TECH Index .HSTECH, which climbs 1.6%

** U.S.-listed stock BILI.O slipped 1.95% on Thursday

** Chinese video streaming platform's Q4 profit jumps as revenue increases

** Nomura ("neutral") says despite Q4 FY25 beat, profit outlook dented by AI investment

** Citi maintains "neutral" amid muted gaming performance, unexpected AI investments

** Says more investment in AI related products and tools "could potentially drag its margin improvement trajectory"

** Jefferies ("buy") estimates Q1 FY26 gross profit margin to improve slightly q/q; sees operating expense increasing slightly y/y factoring in AI investment in R&D

** YTD, HK stock up 5.9%

(Reporting by Donny Kwok)

((donny.kwok@thomsonreuters.com))