By Suzanne McGee

Dec 5 (Reuters) - MFS Investment Management, the Boston-based asset manager that unveiled the world's first open-ended mutual fund a century ago, is making a foray into exchange-traded funds with the launch of five ETFs on Thursday.

Three of the ETFs are tied to the stock market, while the other two offer core bond and municipal bond exposure, respectively, the firm said in a press release.

"This is not about launching a new business, but about delivering our existing capabilities to investors in a new vehicle or package, the ETF," Michael Roberge, CEO of MFS, told Reuters.

Investors have piled nearly $1 trillion into ETFs this year, with a booming U.S. stock market and a proliferation of new products fueling the record inflow.

The popularity of ETFs has spurred traditional asset management firms such as Fidelity and Invesco IVZ.N to launch their own offerings in recent years to compete with industry giants like State Street Global Advisors, Vanguard and BlackRock BLK.N.

While MFS was a very early mover in the mutual fund business, launching the Massachusetts Investors Trust fund in 1924, it has been relatively slow to enter the increasingly competitive ETF arena, analysts said.

"There are still some latecomers to this product that have been slower and more cautious," said Bryan Armour, ETF analyst at Morningstar. "As active ETFs have exploded in size, the impetus for them to dedicate resources to ETFs has grown."

ETFs are more liquid than mutual funds, since they can be traded on an exchange throughout the day, and more tax efficient. They also tend to have lower management fees.

The five ETFs are MFS Active Value, MFS Active Growth, MFS Active International, MFS Active Core Plus Bond and MFS Active Intermediate Muni Bond. They mirror existing MFS strategies, Roberge said.

Armour pointed to Tuesday’s debut of the first ETF from Harris Associates L.P., the Oakmark U.S. Large Cap ETF OAKM.P, managed by Bill Nygren, as another recent example of a top mutual fund name moving into ETFs.

(Reporting by Suzanne McGee; Editing by Ira Iosebashvili and Diane Craft)

((Suzanne.McGee@thomsonreuters.com; 917-285-4385;))