Oscar Oscar CEO and co-founder Mario Schlosser, co-founders Kevin Nazemi and Joshua Kushner.
The new funding is said to be led by Fidelity, and $150 million has been committed so far.
In September, Oscar raised $32.5 million from Google Capital at a $1.75 billion valuation.
Previously, Oscar raised more than $300 million from a slew of prominent investors including Khosla Ventures, Oscar cofounder Josh Kushner's own Thrive Capital, Founders Fund, Goldman Sachs, and Google Ventures.
Founded in 2013 by entrepreneur and venture capitalist Joshua Kushner, Microsoft's former director of health care Kevin Nazemi, and former McKinsey & Company computer scientist Mario Schlosser, Oscar rivals established health insurance companies like Aetna and UnitedHealth.
In 2014, Oscar had just 15,000 users signed up. In September 2015, it had 40,000 users. Now, it has 125,000 users. Though Oscar launched in New Jersey and New York, it's since expanded to serve users in Texas and California.
Oscar users can buy health insurance coverage from the marketplaces created under the Affordable Care Act. The company uses technology and design to make its statements and services easy for anyone to understand.
Schlosser told Business Insider last year that in New York, its market share is upwards of 12%. "The biggest reason why we now decided to raise a new round of capital is that we think the opportunity we originally saw is even bigger than we realized early on," Schlosser told Business Insider. "We started three years ago with the very distinct idea of creating a better user interface for healthcare, and most specifically health insurance."
Oscar did not have a comment on reports about its fundraising.