Alphabet, the holding company for Google, looks set to become the world’s most valuable company when stock market trading begins on Tuesday, following the revelation that it poured $3.6bn last year into “moonshot” projects such as driverless cars.

A surge in mobile advertising in the final months of last year, along with the first insight into the full costs of side bets designed to cement the Alphabet’s long-term leadership in the tech world, extended Wall Street’s recent enthusiasm for the company’s stock.

Alphabet’s shares rose more than 6 per cent in after-market trading on Monday, pointing to a market capitalisation of about $550bn, topping Apple’s $540bn. It had already overtaken Apple measured by enterprise value, after stripping out both companies’ net cash, though market capitalisation remains a more widely followed yardstick.