Fears that the economic downturn is sure to affect tech companies have sent Apple's shares tumbling 16%.

Apple's stock has now lost more than one-third of its value over just 1 month.

And this latest blow is the biggest decrease in 7 years for the computing giant.

The shares tumble happened after two brokerages sliced their earning forecasts and stock recommendations for the company.

A spokeswoman for Morgan Stanley told Reuters that it was worried that "consensus estimates have not been revised down to reflect slowing global consumer demand".

Mike Abramsky, analyst from RBC Capital, pointed to the fact that demand for Macs over PCs could drop following research on potential customers.

HP, Dell and Research in Motion also all suffered shares drops.