Axa Equitable Holdings Inc. has added Citigroup Global Markets Inc. as an underwriter for its initial public offering.

Citigroup is the fourth underwriter to join the IPO, alongside Morgan Stanley & Co. LLC, J.P. Morgan Securities LLC and Barclays Capital Inc.

The company's IPO will effectively take a handful of AXA's American businesses public, including Axa Equitable Life Insurance Co. The offering has a proposed maximum aggregate price of $100 million, estimated solely to calculate the registration fee.

Axa said it expects the IPO to occur in the second quarter, although there can be no assurance that it will be completed during the expected timeline.