The X account of the Securities and Exchange Commission announced the approval of an investment product linked to Bitcoin. It wasn’t true.

For 15 minutes, the cryptocurrency industry was euphoric.

At 4:11 p.m. on Tuesday, the official X account of the Securities and Exchange Commission announced that regulators had approved a new investment product tracking the price of Bitcoin, an apparent victory for embattled crypto supporters. Coinbase, a giant crypto exchange, posted a celebratory banner. Crypto executives hailed it as a historic day for the industry. Bitcoin’s price spiked.

Then at 4:26 p.m., Gary Gensler, the chair of the S.E.C., posted that the agency’s account had been compromised, resulting in an “unauthorized tweet.” An S.E.C. spokeswoman confirmed the hack in an emailed statement.