Bill Gates is once again the world's richest person.
The 57-year-old co-founder of Microsoft recaptured the title from Mexican telecoms tycoon Carlos Slim this week, according to the Bloomberg Billionaires Index.
It is the first time Gates has held the mantle since 2007, with his fortune valued at $US72.7 billion, up 16 per cent on the latest year as Microsoft shares have surged to a five-year high.
Shares in Slim's America Movil, the largest mobile-phone operator in the Americas, have dropped 14 per cent this year after Mexico's Congress passed a bill that could quash the billionaire's market dominance. That helped erase more than $US3 billion from the 73-year-old tycoon's net worth.
Most of Gates' fortune is held in Cascade Investment, a holding entity through which he owns stakes in more than a dozen publicly traded companies. Less than a quarter of his fortune is held in Microsoft.
Gates has donated $28 billion to the Bill & Melinda Gates Foundation and since his retirement in 2008 he has focused on philanthropy.
Berkshire Hathaway chairman Warren Buffett is the world's third-richest person with $US59.7 billion, according to the Bloomberg ranking. He is $US3.7 billion ahead of Spain's Amancio Ortega, Europe's wealthiest person, whose Inditex fashion group owns the Zara chain of clothing and accessories shops.
Google co-founders Larry Page and Sergey Brin have seen their fortunes rise more than 22 per cent as shares of world's most popular search provider have surged. They rank No. 18 and 19 respectively.
■Bill Gates will take part in a special version of the ABC's Q&A program on a visit to Australia this month. He will front a debate about global health and development at the invitation-only event, moderated by host Tony Jones on May 28.