ING U.S., the insurance unit of ING Group, priced 65.2 million shares of common stock at $19.5 per share, which is below the previously announced estimated price range. 

The shares are expected to begin trading Thursday on the New York Stock Exchange under the ticker symbol "VOYA."

The initial public offering will consist of both a primary component of shares offered by ING U.S. and a secondary component of shares offered by ING Group.

The underwriters have the option for 30 days to purchase up to an additional 9.8 million of ING U.S. shares from ING Group at the IPO price, corresponding to a maximum 15% of the total amount of shares offered.

The proceeds of the offering will be used to pay off debt. 

Following the IPO, ING intends to divest its remaining stake in ING U.S. over time, as previously agreed with the European Commission. The company also expects to rebrand as Voya Financial following the offering. 

Morgan Stanley (MS)Goldman Sachs (GS) and Citigroup (C) were the joint book-running managers for the offering.