Under the plan, Bharti Airtel is looking to sell new shares worth 250 billion rupees ($4.8 billion) for 220 rupees apiece, nearly 30% discount to its current stock price, and raise 70 billion rupees via foreign-currency denominated perpetual bonds.
After the rights offering, Singtel's effective interest in Airtel will be 35.2%. Singtel has a direct equity stake of about 15%, according to Refinitiv data.
"Our participation in this rights offering ... reflects our long-standing commitment to Airtel and the confidence in the future of the Indian market," Arthur Lang, CEO of Singtel's International Group, said.
Bharti Airtel's two other major shareholders -- Bharti Group and Bharti Telecom -- intend to subscribe to their full entitlement, while Singapore's state-backed GIC will commit about 50 billion rupees, Bharti Airtel and Singtel said.
Rising competition in India and waning profits at Bharti Airtel, which reported in January that its quarterly earnings plunged by three quarters, also had a knock-on impact on Singtel, Southeast Asia's largest telecom operator.
Last month Singtel reported a 14% drop in third-quarter net profit, hurt partly by intense competition in India that hit Airtel.
