The US Securities and Exchange Commission said Monday it has imposed charges and fines of $63.1 million against nine investment advisers and three broker-dealers for failures to maintain and preserve electronic communications in violation of federal securities laws.

The firms have admitted to the facts spelled out by the SEC and acknowledged that they violated recordkeeping provisions of the federal securities laws, the regulator said.

"Each of the SEC's investigations uncovered the use of unapproved communication methods, known as off-channel communications, at these firms," the regulator said.

The SEC said the companies -- which include Blackstone (BX), KKR (KKR), Charles Schwab (SCHW), Carlyle Group (CG) and Santander (SAN) -- have also begun changing their policies to address the violations.