In a year when major insurers like Aetna and Humana are pulling out of state exchanges left and right — leaving some 35,000 people in 45 counties with no insurance options, and 3 million more in 1,388 counties with just one — a growth story like Oscar's is not only rare, it's virtually unheard-of.

This five-year-old upstart insurance company (currently offering individual coverage in New York, California and Texas) aims to expand its individual market to three new states and offer plans for businesses in four new states by 2018. Oscar reports that engagement with its key features is up 35 percent year-over-year, and that 23 percent of members use its telemedicine feature — eight times the national average of 3 percent.

It launched in 2012 because cofounders Mario Schlosser and Josh Kushner (yes, Jared's brother) were experiencing separate health incidents and took note of how difficult and confusing it was to navigate their health care plans. "No one was there to help them along the way," explains Sophia Norella, director of Oscar for Business and team member at Oscar since 2013.