The number of employers participating in Mercer L.L.C.'s private health insurance exchange will jump next year.

In 2016, 306 employers with more than 1.4 million employees, retirees and dependents will participate in the Mercer Marketplace. That compares with the 247 employers with just over 1 million employees, retirees and dependents who offered coverage through the exchange in 2015.

The growth in employer participation in the Mercer exchange for coverage for employees and dependents is especially sharp. In 2016, 222 employers will offer coverage through the Mercer exchange to 1.4 million individuals, including 633,000 employees. That's a big increase from this year, when 170 employers offered coverage through the exchange to 975,000 individuals, including 440,000 employees.

In addition, 84 employers next year will extend retiree health care coverage to 70,000 individuals, up from 77 employers and 60,000 lives in 2015.

“We are pleased to show growth in both number of clients and number of participants for Mercer Marketplace,” Mercer President and CEO Julio Portalatin in New York said in a statement.

Benefit experts note private health insurance exchanges are appealing to both employers and employees.

The exchange model typically deploys a defined contribution approach in which employers provide a fixed contribution and employees pay more or less for their share of the total premium depending on the level of coverage they choose. Through that approach, an employer can cap what it will pay for health plan coverage for its employees.

Mercer, for example, said medical plan cost savings can be as much as 15% in the first year an employer moves to a private exchange, with smaller cost increases in succeeding years compared to directly offering coverage.

The Mercer exchange “drives sustainable savings for our clients by improving their buying power, optimizing their program offerings and offering more choice, better health care management and consumer decision support tools. We enable a comprehensive strategy that better engages employees and their families, improves their benefit options and produces ongoing savings,” Sharon Cunninghis, global leader of Mercer Marketplace in New York, said in an email.

At the same time, exchanges typically offer employees more plan choices than their employers previously provided.