Health insurer CareConnect more than tripled its enrollment during the latest sign-up period for coverage, which ended Jan. 31.

The health plan, a subsidiary of Northwell Health, signed up 91,193 members. Last year, it had 26,567 members.

Much of that bump was likely the result of the demise of startup insurer Health Republic, which left 200,000 members without coverage when regulators shut it down. CareConnect, in its announcement, attributed the increase to robust growth in the small-group market, which now makes up 60% of its membership, or approximately 54,700. That represents a 526% increase from the same period a year earlier.

Northwell Health's decision to offer the plan to its own employees, of whom 1,500 signed up, also boosted enrollment.

"We launched CareConnect because we believed that a new kind of customer-focused health insurance could actually make it easier to get and stay healthy, and we're gratified to be able to bring our new approach to so many new members," Alan Murray, president and chief executive of CareConnect, said in a statement. The company was founded in 2013 to coincide with the launch of New York's state insurance marketplace, a product of the Affordable Care Act.

The enrollment spike comes after the collapse of Health Republic, a Manhattan startup insurer that quickly grew to more than 200,000 members but was ultimately shut down by state and federal regulators. Health Republic had the largest market share among insurers offering coverage on the state's Small Business Health Options (SHOP) marketplace and a substantial presence on Long Island.

CareConnect seems to have benefited from many consumers who were forced to look for a new health plan. What remains to be seen is how the rush of former Health Republic members to other plans will affect those insurers financially. Health Republic ran into trouble when the premiums it collected weren't enough to cover members' claims.

Through the first three quarters of 2015, CareConnect lost $21.4 million. Mr. Murray had previously said that it would take several years before the insurer would be profitable. The East Hills, Long Island-based company now employs 260 workers, up from 180 at the start of 2015.

Jonathan LaMantia writes for Crain's New York Business, a sister publication of Business Insurance.