New Delhi (CNN Business) India's second-richest man is giving billions to charity in what may be the country's biggest single donation ever.

Wipro WIT Azim Premji, the billionaire chairman of, is handing shares in the tech company worth nearly 530 billion rupees ($7.5 billion) to his philanthropic foundation.

The tech tycoon has now donated a total of $21 billion to the Azim Premji Foundation over several years, including 67% of Wipro's shares, the foundation said in a statement.

Premji, 73, has a fortune of more than $18 billion, according to the Bloomberg Billionaires Index.

He was the first Indian to sign the Giving Pledge, a campaign started by Warren Buffett with Bill and Melinda Gates to encourage billionaires around the world to commit most of their wealth to charity.

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