Shares in PC-maker Compaq fell sharply in after-hours trading, following a profits warning announced after the markets closed in New York yesterday.Shares fell by six per cent on its closing price of $20.77. The company has joined the ranks of PC makers suffering from a sales slowdown, revealing it will miss its revenue targets by almost $1bn. It expects turnover to reach $11.4bn, eight to ten per cent lower than the $12.3bn analysts had been expecting. The PC and chip sector has been hit by a swathe of profit warnings in recent months, contributing to the massive tech stock falls. Apple, Gateway, HP and Intel have all reported diminished revenue expectations.