The Securities and Exchange Commission has collected thousands of staff’s private messages from more than a dozen major investment companies as part of its probe into Wall Street’s use of private messaging apps, according to Reuters.

The regulator is reviewing messages discussing work sent on personal devices or applications from employees at firms including Blackstone Inc., Apollo Global Management Inc. and Carlyle Group Inc., Reuters said, citing people with direct knowledge of the matter that it didn’t name.

Earlier probes into broker-dealers saw the SEC ask companies to report back to the agency on staff messages with regulators reviewing only a sample of messages, Reuters said, citing three people with knowledge of previous investigations.

Spokespeople for the firms and SEC declined to comment to Reuters.

The move underlines the broad reach of the latest phase of US regulators’ crackdown on Wall Street’s failure to keep records.

Filings and media reports show that regulators have quizzed more than a dozen other firms about the use of unofficial channels like WhatsApp, personal texts and email to conduct business. The list includes some of the biggest names in asset management, private equity and hedge funds, as well as smaller banks beyond the Big 6 that have already reached settlements.

Total fines for the probes into messaging practices have now crossed $2.5 billion since December 2021, making this one of the biggest financial enforcement efforts of the past decade.

Brokers and investment advisers are required to monitor and save communications involving their business to head off misconduct. When they don’t, regulators say it’s harder to investigate any wrongdoing. Their work is made even more difficult when bankers use messaging tools that delete communications automatically.

This article was provided by Bloomberg News.