Tech companies are among the firms suffering from the hostile stock market environment as concerns over Chinas financial growth sends global stock markets into free fall, tanking prices.

Compared to Fridays closing price, Facebook opened down 12.1 per cent on the NYSE, at $75.62 (£48.02), Amazon was down 6.4 per cent to $463.03, Microsoft was at $40.59, down 5.8 per cent and Apple had dropped 10 per cent to $95.17.

Smaller companies including Netflix, PayPal and Twitter suffered similar drops between five and 15 per cent as hundreds of billions in market capitalisation disappeared overnight in reaction to Chinas worst trading day since 2007.

Some analysts have expressed fears that tech companies are suffering disproportionately high losses due to the importance of the Chinese market for growth and manufacturing, while others have warned that companies preparing for IPOs like Uber may well delay to see whether todays drops have long-lasting implications.

Tim Cook, CEO of Apple made the unprecedented move of sending an open email to financial analyst and TV presenter Jim Cramer, stating that Apple was still performing well in China, and that many of the fears over the countrys long-term financial stability were overblown.

“We have continued to experience strong growth for our business in China through July and August,” said Cook. “Growth in iPhone activations has actually accelerated over the past few weeks, and we have had the best performance of the year for the App Store in China during the last two weeks.

“Obviously I cant predict the future, but our performance so far this quarter is reassuring. Additionally, I continue to believe that China represents an unprecedented opportunity over the long term as LTE penertration is very low and most importantly the growth of the middle class over the next several years will be huge.”