Nvidia has handed back the position as the world's most valuable company to Microsoft after its share price fell by more than 3.5% on Thursday. The artificial intelligence (AI) chip giant briefly held the top spot from Tuesday, with a stock market valuation of 3.34tn ( 2.64tn). But Nvidia's shares fell to 130.78 on Thursday, sending its value down to around 3.22tn, with Microsoft reclaiming the title as it held steady at more than 3.3tn. Nvidia's rise has been fuelled by its dominance of what analysts call the "new gold or oil in the tech sector" - the chips that power AI. Nvidia, Microsoft and Apple - each worth more than 3tn - are in a three-horse race to be the world's most valuable company.

Despite its status as the world's most valuable firm, Apple has for some time been thought to lag its biggest rivals in developing one of today's most valued technologies. In the artificial intelligence (AI) battle, it still looks a relative weakling next to the likes of Amazon and Google. No wonder that when Light Reading polled readers in February, asking them what Apple Inc. (Nasdaq: AAPL) should spend its billions on, the most popular response was artificial intelligence and machine learning. But Apple this week may have found a far less costly way of closing the AI gap. Rather than splurging billions on touted AI startups, it has poached one of the smartest AI experts from one of its main competitors. According to a report from the New York Times (NYT), the executive in question is none other than John Giannandrea, the head of search and artificial intelligence for Google.