Apple has cut its sales forecast for its end of year period, placing the majority of the blame on an unforeseen scale of economic slowdown in China. The announcement wiped more than seven per cent off of the iPhone maker’s shares, equating to a $55bn loss in value.

Apple’s CEO Tim Cook addressed an open letter to investors, informing them that the company now expects to achieve around $84bn in revenue for the first quarter of its fiscal year 2019, which ended on 29 December. This is down on the between $89bn and $93bn previously forecasted.

“While we anticipated some challenges in key emerging markets, we did not foresee the magnitude of the economic deceleration, particularly in Greater China,” wrote Cook. “In fact, most of our revenue shortfall to our guidance, and over 100 per cent of our year-over-year worldwide revenue decline, occurred in Greater China across iPhone, Mac and iPad.”

In addition to the generally unideal economic climate in China, Cook cites trade tensions between the US and China as having an impact on the economy – with US president Donald Trump and China’s president Xi Jingping still at loggerheads.

Despite the economic challenges in China, Apple still believe that its business has a “bright future” there.

“The iOS developer community in China is among the most innovative, creative and vibrant in the world,” said Cook. “Our products enjoy a strong following among customers, with a very high level of engagement and satisfaction. Our results in China include a new record for Services revenue, and our installed base of devices grew over the last year. We are proud to participate in the Chinese marketplace.”

Cook also highlighted that, though the state of macroeconomics can be mostly blamed, iPhone upgrades were weaker than expected; there are fewer carrier subsidies for consumers; the US dollar is strong; and customers are taking advantage of a programme where Apple replace iPhone batteries for a lower price.

Apple’s announcement managed to hit tech stocks as a whole with the likes of Amazon, Microsoft, Facebook, Alphabet, Alibaba, and other big names all taking it hit in after-hours trading.