** Hong Kong shares of Hua Hong Semiconductor 1347.HK drop 9.3% to HK$102.8, on course for biggest one-day pct decline since February 2

** Stock hits the lowest since April 24 in its second session of decline; top pct loser in the Hang Seng TECH Index .HSTECH, which rises 1.5%

** Shanghai-listed stock 688347.SS falls 7% to 128.4 yuan, on track for biggest one-day pct drop since March 2

** The U.S. Department of Commerce last week ordered multiple chip equipment companies to halt certain tool shipments to China's second-largest chipmaker, Hua Hong, its latest action to slow the country's development of advanced chips, according to two people familiar with the matter

** The department sent letters to at least a handful of companies informing them of the new restrictions on tools and other materials destined for two Hua Hong 688347.SS facilities that U.S. officials believe may make China's most sophisticated chips, the sources said

** Hua Hong did not immediately respond to a request for comment

** YTD, Hua Hong's Hong Kong shares up 41.1%, Shanghai-listed stock up 21.2%