WASHINGTON (Reuters) - Wall Street firms including Blackstone, Apollo Capital Management and Carlyle have agreed to pay more than $63 million for violating U.S. Securities and Exchange Commission rules over record-keeping, the regulator said on Monday.

The investment advisers and broker-dealers also admitted they violated rules in connection with employees' use of off-channel communications platforms such as WhatsApp, the SEC said in a statement.

The funds are the latest of dozens of Wall Street firms that have paid stiff penalties over the last few years to settle related charges. The SEC's investigative sweep, launched in 2021, has been a major initiative under outgoing SEC chair Gary Gensler that has ensnared big banks and others.

As part of the settlements announced on Monday, the firms acknowledged their conduct violated record-keeping provisions, and have begun implementing improvements to their compliance policies and procedures, the SEC said.

The firms are:

* Blackstone Alternative Credit Advisors LP * Blackstone Management Partners LLC * Blackstone Real Estate Advisors LP * Kohlberg Kravis Roberts & Co. LP * Charles Schwab & Co * Apollo Capital Management LP * Carlyle Investment Management LLC * Carlyle Global Credit Investment Management LLC * AlpInvest Partners B.V. * TPG Capital Advisors LLC * Santander US Capital Markets LLC * PJT Partners LP