The US Securities and Exchange Commission (SEC) has charged four former senior Merrill Lynch executives with helping Enron to commit securities fraud in deals designed to illegally boost the bankrupt energy group's profits.

Thomas Davis, former vice-chairman of Merrill Lynch and once a contender for the post of chief executive, was among the four charged by the SEC. The others were Daniel Bayly, former head of investment banking, Schuyler Tilney, who headed the energy investment banking group and Robert Furst, a member of Tilney's team.