Mitchell Steinhause, chairman of the New York Mercantile Exchange, has told the board he will not seek to be re-elected as the commodities market moves towards a flotation.

His decision to step down comes a week after 90% of Nymex's members approved an investment in the commodities market by private equity firm General Atlantic, and two weeks after the exchange was forced to admit defeat over a open outcry market in London which will now switch to electronic trading.