(Bloomberg) -- Blackstone Group will pay almost $39 million to settle claims stemming from a U.S. regulator's industrywide investigation into whether private equity firms put their own interests ahead of investors'.

The sanction resolves allegations that the world's largest private equity manager failed to fully inform investors about fees and business discounts that benefited the firm, the U.S. Securities and Exchange Commission said in a statement Wednesday. The accord includes a $10 million fine, and $28.8 million of disgorgement and interest.

"Transparency of fees and conflicts of interest is critical in the private equity industry and we will continue taking action against advisers that do not adequately disclose their fees and expenses, asBlackstone did here", Andrew Ceresney, director of the SEC's enforcement division, said in the statement.

Blackstone, which didn't admit or deny the allegations, is the biggest private equity manager to face scrutiny in the SEC's review of obscure fees that firms keep for themselves and charges that are passed on to investors.

KKR & Co. in June agreed to pay a $10 million fine and disgorgement of about $18.5 million to settle allegations that it allowed some investors, including the firm's executives, to sidestep costs tied to unsuccessful corporate buyouts.

Blackstone in May said regulators asked for more information about the New York-based firm's disclosures of what's known as vendor discounts, which includes rebates the firm received from law firms it routinely hired.

The SEC also asked Blackstone for more transparency of monitoring fees, which private equity firms charge the companies they own annually for services like administrative, legal and advisory work. The SEC has been reviewing instances in which private equity firms forced portfolio companies to make accelerated, lump-sum payments, even though the work hadn't been done yet. The fees were collected early because the businesses were being sold.

Blackstone said it expanded its disclosure of the practices to investors after an SEC exam that spanned from 2011 to 2012. The firm also said that last year it stopped collecting monitoring fees from companies it sells and limited the practice after taking businesses public.

"This SEC matter arose from the absence of express disclosure in marketing documents, 10 or more years ago, about the possible acceleration of monitoring fees, a common industry practice," Blackstonespokesman Peter Rose said in a statement Wednesday. "Each accelerated fee was, however, as the SEC order acknowledges, disclosed when received and our limited partner advisory committee did not exercise its right to object. Moreover, Blackstone voluntarily made changes to the applicable policies well before this inquiry was begun."

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