Apple shares took a hammering last night, losing 45 per cent of their value on the after-hours market, closing at $29.1875.

The fall obliterated over $7 billion of Apple’s market capitalization.

The tumble followed an unexpected profit warning from Apple, which had expected to return yet another profitable quarter. The company has warned investors that it now expects its fourth-quarter earnings to fall short of expectations by as much as 33 per cent.

Apple’s chief financial officer, Fred Anderson blamed a drop in sales for the problem. He revealed that this has affected all Apple’s markets. Education sales have also been slower than expected, while G4 Cube sales have also started slowly. Apple CEO, Steve Jobs said: "We’ve clearly hit a speed-bump."

Apple said it expects to report revenues between $1.85 billion and $1.9 billion. In light of the slowdown, the company will reduce its growth targets for its next fiscal quarter and year. Revised targets will be provided when the company makes its fourth-quarter results announcement on October 18. The post-profit warning Q4 earnings represent 30-33 cents earnings per diluted share, against previous analysts’ expectations of 45 cents per share.

Analysts have been surprised by Apple’s warning, saying they have no immediate insight on whether the problems are specific to the company or caused by the global economy. Similar problems have afflicted Intel, which has also warned of lower-than-expected third-quarter revenues.

Ruth Carpenter, senior analyst at IDC, told Macworld: "This is traditionally a very slow quarter in the PC industry. Apple’s last quarter [Q3] was particularly good in terms of consumer sales. We were expecting a poor third quarter, but the industry as a whole benefited from increased consumer shipments."

Technology stocks across the board are expected to suffer as a result of Apple’s announcement. Dell, Sun, Gateway and Compaq also dropped in value yesterday. Intel warned last week that its sales would lag, which sparked a major sell-off in tech stocks the next day.

Apple was unavailable for comment.