** Hong Kong shares of Chinese search engine leader Baidu 9888.HK jump as much as 12% to HK$99.6, their highest since Oct. 14, on course for second consecutive session of gains

** Stock on track for its biggest one-day pct rise since March 2023, if gains hold

** Baidu said on Thursday it would make its artificial intelligence chatbot Ernie free starting April 1, citing improved technology and reduced costs

** The AI service will be accessible at no cost to all users on both desktop and mobile platforms, Baidu said in a WeChat post

** U.S.-listed stock rose 4.3% on Wednesday

** Hong Kong stock fell 28.8% last year, U.S. shares dropped 29.2%

(Reporting by Donny Kwok)

((donny.kwok@thomsonreuters.com))