Sunil Mittal has emerged as the biggest billionaire gainer in 2025, with a $4.3 billion rise in net worth, surpassing Mukesh Ambani and Gautam Adani in year-to-date wealth growth. The rally in global stock markets, sparked by tariff relief from US President Trump, boosted performance by Airtel, and wealth gain by Mittal. Ambani and Adani also saw gains.