Stephen Schwarzman, one of Wall Street’s most prominent deal makers, is going out of his way to keep the details of his personal fortune a closely held secret.

Blackstone Group LP is changing the structure of its investment in a Florida bank after Mr. Schwarzman, founder and chief executive of the private-equity firm, balked at providing information about his personal finances to the Federal Reserve, according to people familiar with the situation.



Blackstone is converting part of its 14.1% stake in BankUnited Inc. to nonvoting preferred stock, these people said. The deal will shrink its voting stake to less than 10%, pushing the New York firm below the level at which the Fed requires personal financial data from the Florida bank’s owners.

It isn’t clear why Mr. Schwarzman is sensitive about providing such information. The longstanding Fed rule is in place to allow the regulator to gauge the safety of banks by evaluating the financial resources of their owners. The financial information gathered about a bank’s owners isn’t available to the public, even if requested under the Freedom of Information Act, according to people familiar with Fed policies.

Many details of Mr. Schwarzman’s personal wealth already have been disclosed, particularly since Blackstone went public in 2007. At that time, the company reported that it had paid Mr. Schwarzman $398.3 million in 2006.

Mr. Schwarzman ranks as the 66th richest American, with an estimated net worth of $4.7 billion, according to Forbes. He is tied for that spot with real-estate mogul Sam Zell and Robert Rowling, an oil tycoon who also owns the Omni hotel chain, according to the Forbes ranking.

Principals of the private-equity firms WL Ross & Co., Carlyle Group and Centerbridge Partners, all of which also have more than 10% stakes in BankUnited, are willing to provide their personal financial information, according to the people familiar with the situation.