New Delhi, Oct. 29: Billionaire Mukesh Ambani today became the richest person in the world, surpassing American software czar Bill Gates, Mexican business tycoon Carlos Slim Helu and famous investment guru Warren Buffett, courtesy the bull run in the stock market.

Following a strong share price rally today in his three group companies — India's most valued firm Reliance Industries, Reliance Petroleum and Reliance Industrial Infrastructure Ltd — the net worth of Mukesh rose to $63.2 billion (Rs 2,49,108 crore).

In comparison, the net worth of both Gates and Slim is estimated to be slightly lower at around $62.29 billion each, with Slim leading among the two by a narrow margin.

Warren Buffett, earlier the third richest in the world, also dropped one position with a net worth of about $56 billion.

Ambani’s wealth of about Rs 2,49,000 crore includes about Rs 2,10,000 crore from RIL (50.98 per cent stake), Rs 37,500 crore from RPL (37.5 per cent) and Rs 2,100 crore from RIIL (46.23 per cent).

Slim’s wealth has been calculated on the basis of his stake in companies such as America Movil (30 per cent), Carso Global (82 per cent), Grupo Carso (75 per cent), Inbursa (67 per cent), Ideal (30 per cent) and Saks Inc (10 per cent).

According to information available with the US and Mexican stock exchanges where these companies are listed, Slim currently holds shares worth a total of $62.2993 billion, with more than half coming from Latin American mobile major America Movil. Slim is closely followed by Gates with a net worth of $62.29 billion.

Earlier last month, US business magazine Forbes had named Gates as the richest American with a net worth of $59 billion, calculated as on August 30.

The magazine had said that a movement of two dollars in the share price of Microsoft, the world's biggest software maker, could “add or subtract a billion dollars” from his wealth.

Since August-end, Microsoft's share price has risen by $6.58 (based on yesterday's closing on Nasdaq at $35.03), which results in a gain of $3.29 billion in Gates’s wealth based on Forbes assumption.