SAN FRANCISCO: Shares of Apple sank below $90 for the first time in nearly two years on Thursday, ceding the title of the world's largest company by market valuation to Google.

With investors souring on the outlook for sales of its market-leading iPhones and iPads, and no new blockbuster consumer electronics product in its offerings, Apple shares fell 3.3 per cent to $89.47 in morning trade Thursday, before rebounding slightly back above the $90 threshold.

That left the company's stock off more than 14 per cent since the beginning of the year and down one-third from the peak of $132.54 one year ago.

Apple stock has slid sharply since mid-April, hit in part by the company's disappointing fiscal second quarter earnings, which showed a decline in revenues and the first quarterly drop ever in iPhone unit sales since launching the smartphone in 2007.

Thursday's fall elevated Google parent Alphabet ahead of its Silicon Valley rival as the world's largest company. At midday Apple's market valuation was around $494 billion against Alphabet's $498 billion.

Worries were mounting over the pace of iPhone sales, the company's top earner, amid reports that consumers worldwide are generally replacing their phones less often than before.

Key Asian producers of components for Apple were also seeing their shares pummelled on the forecast for slower iPhone sales.

And analysts at UBS cut their outlook for Apple's share price on Wednesday to $115 from $120 on lower sales forecasts.