Apple and Amazon have extended their losing runs overnight and have now lost a combined $US100 billion in just four days, despite a rebound in the overall Dow Jones and Nasdaq indices.

Shares of Apple slumped 1.5 per cent in afternoon trading, extending its losing streak to four sessions after closing at a record $US228.36 on September 4.

Yesterday’s $US10.42 fall means the company has lost 4.6 per cent of its total value, or $US50.33 billion, since peaking at $US1.10 trillion, ahead of its upcoming iPhone launches and amid a broader weakening in the technology sector.

Apple’s fall alone was enough to take 71 points off the Dow Jones Industrial Average, though the company is still up 26 per cent in the past 12 months.

Shares in the world’s second-largest company, Amazon.com fell 0.8 per cent, also extending their loss to four sessions, worth a total of $US50.53 billion after briefly joining Apple in the trillionaire’s club.

Chinese internet giant Alibaba also fell nearly 2 per cent after founder and executive chairman Jack Ma announced he was stepping down. The stock is now down almost 25 per cent off its high of three months ago.

On the up side, chip stocks rebounded strongly after a disastrous last week, with Advanced Micro Devices up 2.9% and ASML Holdings was up 3% after falling 12 per cent over the past seven days.