HONG KONG—Hong Kong authorities on Friday froze assets belonging to jailed media tycoon Jimmy Lai, including all shares in his company, Next Digital—the first time a listed firm has been targeted by national security laws in the financial hub. Also among assets targeted were the local bank accounts of three companies owned by him, Hong Kong’s Secretary for Security John Lee said in a government statement. The statement, issued after the market close, said Lee had issued notices “in writing to freeze all the shares of Next Digital Limited held by (Jimmy) Lai Chee-ying, and the property in the local bank accounts of three companies owned by him”. Lai was sentenced to 14 months in prison for taking part in unauthorized assemblies during pro-democracy protests in 2019. He faces three alleged charges under a sweeping new national security law imposed by Beijing, including collusion with a foreign country. The move …