The Indian billionaire Gautam Adani has surpassed Bill Gates to become the fourth richest person in the world.

The Indian businessman has amassed an additional US$36 billion in wealth this year, more than anyone else, whereas Gates' fortune has dropped as a result of his increased humanitarian donations and the decline of tech stocks.

According to the Bloomberg Billionaires Index, Adani's net worth increased to US$112.5 billion (S$156 billion) on July 21, surpassing the Microsoft co-founder by US$230 million.

His rapid diversification into renewable energy, airports, data centers, digital services, and media is in line with Indian Prime Minister Narendra Modi's ambition for nation-building.

Adani, whose fortune was earned on agri-trading, coal, and ports, is climbing up the wealth ladder previously dominated by U.S. technology innovators.

In April this year, Adani became a centibillionaire, joining the ranks of billionaires such as Elon Musk and Jeff Bezos.

The college dropout and first-generation entrepreneur who founded an agri-trading company in the late 1980s has amassed nearly all of his riches in the past two years as his efforts to diversify have escalated.

Recently, he has been exploring potential partnerships with Aramco, including the possibility of purchasing a stake in the Saudi petroleum giant, was in advanced talks to acquire Holcim's cement businesses in India, and signed an agreement to explore business opportunities with South Korea's steel producer Posco.

Given his group's interest in constructing the Carmichael coal mine project in Australia, his November plan to invest US$70 billion across the green energy value chain by 2030 is frequently criticized by environmentalists.

Adani Enterprises, the group's flagship company, said in April that it had launched a new media division, signaling his intent to access the rapidly expanding local entertainment sector.

His rise coincided with a philanthropic boost from the world's wealthiest individuals. Gates announced earlier this month that he is donating $20 billion to his foundation, which would exceed the $15 billion he and his ex-wife pledged in 2021.

The previous year's pledge was factored into the wealth index when he made the announcement, and an additional US$5 billion was added to that responsibility for the new pledge, bringing Gates' net worth to slightly below that of Adani.

Meanwhile, Warren Buffett, who has dropped to No. 7 on the list, has donated almost $35 billion to the charity, including $3.1 billion in June alone.

To celebrate his 60th birthday in June, Adani committed to donate $7.7 billion to various charitable projects.