The vulnerability of governments and businesses to cyberattacks was exposed again Wednesday when a top U.S. financial regulator said hackers had breached its electronic database of market-moving corporate announcements, and may have profited from the information they stole.

The hack of an aspect of the U.S. Securities and Exchange Commission's Edgar filing system occurred last year, the regulator said in a statement. While the SEC has been aware of the breach since 2016, it wasn't until last month that the agency concluded that the cybercriminals involved may have used their bounty to make illicit trades. The regulator disclosed the intrusion for the first time Wednesday.

Edgar houses millions of filings on corporate disclosures ranging from quarterly earnings to statements on mergers and acquisitions. Infiltrating the SEC's system to review announcements before they are released publicly would serve as a virtual treasure trove for a hacker seeking to make easy money.