New Delhi, June 24 -- Meta Platforms Inc.'s decision to hand leadership of WhatsApp to Kunal Shah, one of India's most prominent angel investors and the founder of fintech star Cred, started with a cold email.

Meta Chief Product Officer Chris Cox reached out to Shah directly in the spring, seeking advice on picking the future leader of WhatsApp. Cox had been calling entrepreneurs and investors in places like India, Brazil and Mexico, countries where WhatsApp is a dominant part of business and culture, and Shah's ideas about the future of the app left an immediate impression.

"He had an incredible set of answers," Cox recalled in an interview. "At the end of the call, I asked him if maybe he and I should talk about him doing it."

On Mon...