4 Indians In Fortune's '40 Under 40' Powerful People List

Last year, Chetty won the John Bates Clark Medal, also known as the "baby Nobel", given to the best economist under the age of 40. Chetty, who earned his Ph.D at Harvard by age 23, now oversees a staff of 10 researchers, a job "he does not take lightly."

"My biggest nightmare is always that someone is going to have made an error in the thousands of lines of code that are involved in these projects and that feeds into some public policy thing," Fortune quoted him as saying.

Sharma, 37, started Micromax as an IT software company but he hit upon a "winning formula" by making cheap cell phones with a month-long battery life.

In five years since founding the company, handset sales have grown from 10,000 to 36 million and revenue hit $500 million last year.

"That could scale much bigger now that it has a deal with Google to make its sub-$100 phones for the Indian market, seen as the next big area of growth for the global tech giants," Fortune said, adding the company even hired renowned Australian actor Hugh Jackman as its brand ambassador.

Bahl, 31, co-founded Snapdeal with high school friend Rohit Bansal and in less than three years, the online marketplace has exploded to become India's largest.