Beset by accusations of insider trading entailing a five-year pump-and-dump scheme, Ladenburg Thalmann Financial Services Chairman Phillip Frost retired from his position.

Ladenburg Thalmann’s board of directors has appointed Richard Lampen, CEO and president, to serve as chairman. Adam Malamed, executive vice president and chief operating officer, was also appointed to the board.

Frost, 81, announced his retirement, effective immediately, on Thursday in a company release.

“I have decided to retire from the Ladenburg Board and will concentrate my efforts on OPKO Health and my philanthropic interests,” said Frost in the release. “As a long-term shareholder, I am confident in Ladenburg’s outlook and look forward to its continued growth and success.”

Earlier this month, Frost was among those in a 10-member investor group charged with securities fraud for allegedly manipulating penny stocks in a scheme that left many investors holding worthless shares. Frost currently serves as CEO of OPKO, a Miami-based biotech company targeted in the scheme.

According to recent filings, Frost, a billionaire biotech executive and investor, owned about 33 percent of Ladenburg.

In its complaint, the U.S. Securities and Exchange Commission requested that the investors disgorge $27 million in ill-gotten gains and be barred from future offerings and promotions of penny stocks.

In a company statement, OPKO later claimed that the SEC's charges were based on "factual inaccuracies."

Ladenburg Thalmann, which names Securites America, Investacorp and Triad Advisors among its subsidiaries, did not give a reason for Frost’s retirement on Thursday.

“We thank Phil for his service to Ladenburg and its shareholders over the past 14 years,” said Lampen in released comments. “Ladenburg would not be where it is today without his many contributions, and his presence in the boardroom will be sorely missed.”