(Reuters) - TIAA-CREF, a retirement services provider to non-profit organizations such as universities and hospitals, said it would acquire asset manager Nuveen Investments for $6.25 billion, seeking to expand its mutual fund and municipal bond offerings.

The deal will add more than $221 billion in assets to TIAA-CREF's roughly $569 billion in assets under management, broadening its portfolio with closed-end municipal bond funds which offer regular, annuity-type payouts.

It also offers relief to Nuveen's current owner, private equity firm Madison Dearborn Partners LLC. Madison Dearborn will break even on the deal, according to a person close to the firm, having taken Nuveen private in 2007 for $5.8 billion and saddled it with debt that weighed on its earnings.

The deal is expected to close by the end of the year, pending approval from existing Nuveen clients and antitrust regulators.

Lazard Ltd and J.P. Morgan Securities LLC advised TIAA-CREF. Bank of America Merrill Lynch, Wells Fargo Securities LLC and Citigroup Global Markets acted as financial advisors to Nuveen Investments. UBS Investment Bank, Goldman Sachs & Co and Moelis & Co acted as financial advisors to the Nuveen management team.