(Reuters) - Dutch financial services group ING Groep NV's (>> ING GROEP) U.S. unit raised $1.3 billion (835.1 million pounds) in its initial public offering on Wednesday, less than expected, though the offering ranked as the second largest U.S. float of the year behind Zoetis Inc (>> Zoetis Inc).

ING U.S. sold more shares than expected but at a price that was below the marketed range. It sold 65.2 million shares at $19.50, according to an underwriter. It had intended to price 64.2 million shares at a range of $21 to $24.

The shares were offered by both ING U.S. and its parent. The proceeds for ING U.S. from the offering are intended to be about $600 million.

ING Groep is splitting its banking and insurance operations as part of a restructuring agreement with the European Commission, turning into a smaller Europe-focused bank.

The group received a 10 billion euro ($12.71 billion) capital infusion from the Dutch government in 2008 and has been selling assets to repay the bailout. It sold its U.S. online banking business ING Direct USA for nearly $9 billion to Capital One Financial Corp (>> Capital One Financial Corp.) in 2011.

ING Groep's ownership in ING U.S. will fall to 75 percent after the IPO. The parent will shed the rest of its stake by 2016.

ING U.S., which is led by former American International Group Inc (>> American International Group Inc) executive Rodney Martin, provides insurance, retirement and investment services and competes with companies like MetLife Inc (>> Metlife Inc) and Prudential Financial Inc (>> Prudential Financial Inc).

It has roughly 13 million customers and reported net income of $473 million last year. According to the American Council of Life Insurers, it ranks among the 10 largest life insurers in the United States by assets and individual policies issued.

Like peers, ING has been forced to deal with a persistently low interest rate environment, which means lower returns on investment portfolios.

Actuaries have suggested that if rates remain this low for just a few more years, some insurers will have to rethink their businesses entirely, given the risk that they may not be able to generate sufficient returns to cover their obligations.

When it first filed to go public in November, ING U.S. said it intended to rebrand itself after listing and that it expected "substantial costs" in connection with the rebranding. However, the company does not expect to shift to the new brand name of Voya Financial until 2014.

It also expects the rebranding to take about 24 months and cost $40 million to $50 million, excluding incremental advertising expenses.

U.S. IPO proceeds have risen 22 percent so far this year to $36.9 billion as of May 1, according to Thomson Reuters data, boosted by public floats from companies tied to the housing market and those offering dividend yields to investors like REITs and MLPs.

ING U.S. will list on the New York Stock Exchange under the symbol VOYA.

Morgan Stanley (>> Morgan Stanley), Goldman Sachs Group Inc (>> Goldman Sachs Group, Inc.) and Citigroup (>> Citigroup Inc.) led the IPO.

(Reporting By Olivia Oran in New York; additional reporting by Ben Berkowitz; Editing by Leslie Adler)

By Olivia Oran