CVS Health will sell flexible spending and health savings account provider PayFlex to financial services firm Millennium Trust, the companies announced Tuesday.

The companies said the deal is expected to close in the second quarter. CVS Health and Millennium Trust Company did not disclose the financial terms of the transaction. CVS Health’s Aetna insurance subsidiary will retain PayFlex as its preferred provider of HSA, FSA and other tax-advantaged consumer accounts.

CVS Health There was no immediate response to an interview request.

“This acquisition expands Millennium Trust’s core business and complements our robust retirement solutions,” Millennium Trust CEO Gary Anetsberger said in a statement. Press Releases.

PayFlex offers Medical Flexible Spending Accounts, Health Savings Accounts, Health Reimbursement Arrangements and Dependent Care Flexible Spending Accounts.

As of June, HSA’s assets had grown to $92.9 billion in more than 31 million accounts, according to the latest data from HSA consulting group Devenir. Balances rose 26% year over year, and the number of accounts rose 6%. Data shows that HSA assets have doubled in the past three years.

PayFlex currently has accounts held by more than 2,500 employer clients and 2.4 million individual clients. The acquisition will nearly double Millennium Trust’s account count to 5 million and increase its assets under management to $47 billion.

UnitedHealth Group’s Optum Financial is the nation’s leading HSA provider with more than 8 million accounts. Other top providers include Fidelity Investments, HealthEquity and HSA Bank.

Space also attracts VC-backed competitorThese include FirstDollar, which raised $14 million in Series A funding this year led by Blue Cross and Blue Shield, and Lively, which has raised $122.2 million in venture capital.