David Harding cites "personal reasons" for selling shares

Mr Harding is understood to have sold shares worth about �5m to finance a divorce settlement.

But shares plunged when brokers Seymour Pierce urged investors to "follow the leader" and sell up.

A company share buyback announced on Friday helped to steady William Hill shares at 538 pence, down 1.5p.

The move was part of a long-running share buyback programme approved by William Hill shareholders a month ago.

The company plans to take 10% of its shares out of circulation, with the intention of boosting share prices and returning money to shareholders.

Mr Harding's sale of more than 900,000 shares, however, has spoiled William Hill's plans for now, wiping �75m of the value of the FTSE 100-listed company.

'100% fullycommitted'

When the bookmaker floated on the stock market two years ago, Mr Harding had promised investors that he would keep his shareholding to demonstrate his commitment to the company.

A spokeswoman for William Hill said Mr Harding's attitude was unchanged: "He is 100% fully committed to the company."

As proof she pointed to Mr Harding's long-term incentive plan, which leaves him with 855,556 shares of which he can sell 45% in June 2005 at the earliest, and another 81,508 shares that are locked in for at least three years.

In May William Hill reported that its gross winnings were up 22% in the 19 weeks to 11 May compared with a year ago, as horse racing results went in its favour.

William Hill's share price has soared since flotation, from 225p to 558p before Thursday's fall.