The US Securities and Exchange Commission (SEC) on Tuesday charged Concord Management and its owner with failing to register with regulators while operating as an investment adviser to an unidentified billionaire former Russian official.

Concord Management LLC of Tarrytown, New York, and owner Michael Matlin were operating as unregistered investment advisers to a single client, a former Russian official with apparent connections to the Russian Federation, the SEC said in a statement.

A lawyer for Concord and Matlin did not respond immediately to calls for comment. The New York Times has previously reported that Russian oligarch Roman Abramovich was the firm’s client, but Reuters could not immediately verify that information. A lawyer for Abramovich did not respond to requests for confirmation or comment.

Matlin founded Concord in 1999 to provide investment advice and supervise investments in US private funds, the SEC said. The firm monitored investments for the Russian individual until March 2022, when the United Kingdom and European Union sanctioned the unidentified client, it said.

Over $7 billion of assets belonging to a single foreign individual was “actively managed” in US markets by a single firm without regulatory oversight, the SEC said in its charges.

The SEC’s lawsuit was filed in the southern district of New York.