HONG KONG — A Hong Kong court on Thursday found 14 of 16 pro-democracy activists guilty of conspiring to subvert the state in the Chinese territory’s single largest case under a sweeping national security law imposed by Beijing.

The three judges handpicked by the government to hear the case acquitted two of the defendants, former district councilors Lawrence Lau and Lee Yue-shun, making them the first national security law defendants to be found not guilty after trial.

The defendants are…