A hacker hijacked a US Securities and Exchange Commission staffer’s phone number to make a fake social media post earlier this month, according to the regulator. The post prematurely claimed that the SEC had approved a spot Bitcoin exchange-traded fund to trade in the US.The SEC said on Monday that an unidentified person changed the password for the agency’s account after gaining control of an agency employee’s phone number to make the false post on Jan. 9. The message, which was later deleted, ...