The US stock market regulator is investigating troubled insurance broker Marsh & McLennan’s shareholder transactions, the firm has said.
The Securities and Exchange Commission has asked for information about transactions involving holders of 5% or more of the firm’s shares.
Marsh has said it is co-operating fully with the SEC investigation.
Marsh is also the focus of an inquiry the New York attorney-general into whether insurers rigged the market.
Since that inquiry was launched in October, Marsh has replaced its chief executive and held a boardroom shake-out to meet criticism by lessening the number of company executives on the board.
Prosecutors allege that Marsh – the world’s biggest insurance broker – and other US insurance firms may have fixed bids for corporate cover.
This is the issue at the heart of the inquiry by New York’s top law officer, Eliot Spitzer, and a separate prosecution of five insurers by the State of California.
The SEC’s investigation into so-called related party transactions includes dealings in the Trident Funds, managed by MMC Capital, the company’s private equity firm.
Marsh’s new chief executive, Michael Cherkasky, is trying to negotiate a settlement with Mr Spitzer.
Mr Spitzer has built up a reputation as a fierce critic and campaigner against corporate America’s misdeeds.
The uncertainty unleashed by the scandal has prompted three credit rating agencies – Standard & Poor’s, Moody’s and Fitch – to downgrade Marsh in recent weeks.
According to the Financial Times, insurance analysts are now questioning whether Marsh will be able to maintain its strong record of earning growth as they draw up forecasts for the first quarter of next year.
Doubts also exist over how much the company may have to pay regulators and lawyers to put the scandal behind.