Investors sold off more shares in the largest technology companies on Monday, deepening concerns that the high-value industry is a bubble.

Shares in Apple, Amazon, Facebook, Google and Microsoft were all down when markets opened on Monday, continuing a sell-off that started on Friday.

Apple suffered the biggest drop yesterday, continuing a trend that started before the weekend. The iPhone giant was down 2.5pc, following a 4pc decline on Friday, which slashed $30bn from the company's value. Brokers downgraded the company for a second time in two weeks.

Amazon, Google and Facebook were all down 2pc on Friday and a further 1.5pc on Monday.