Cash was at the root of yesterday's rumours of Microsoft’s settlement with the Department of Justice over its monopoly charge, reports in the US media claim.

Pacific Exchange traders triggered the gossip, when they began buying call options on Microsoft stock, Miller Tabak options trader Robert Koggan told the New York Times online news site, NYTimes.com.

NYTimes.com broke the story, revealing that, although no real antitrust news emerged on Tuesday, there was serious money to be made in speculating it would - even for those who left the stock alone and stuck to options.

Buying one Microsoft call option at the start of the rumours and selling just before the close of trading would have turned a 400 per cent gain.