* Cieszko will replace Fidelity exec who retired Dec. 31

* Orazem steps into role that has been vacant since July

* Fidelity assets down about $400 bln in '08 through Nov (Recasts with details of executives replaced; adds Evergreen comment)

BOSTON, Jan 6 (Reuters) - Fidelity Investments hired two heavy hitters for its institutional group, an arm of the world's biggest mutual funds company that targets advisors and other intermediary clients.

Peter Cieszko was named president of Fidelity Investments Institutional Services Co, which manages $272 billion in assets and provides fund management services through financial institutions and advisors, Fidelity said in a statement on Tuesday.

Cieszko was president of global distribution at Evergreen Investments, the funds arm of Wachovia Corp, which was bought by Wells Fargo & Co (WFC.N: Quote, Profile, Research), the fourth-largest U.S. bank by assets, at the turn of the year.

Cieszko was named in July to the post of Evergreen president and chief executive, effective Jan. 1, and had been transitioning into that role but left the firm at the end of 2008, Evergreen spokeswoman Laura Fay said.

Before Evergreen, Cieszko worked with money manager Legg Mason (LM.N: Quote, Profile, Research).

Cieszko replaces Joe LoRusso, who stepped down on Dec. 31 after previously announcing his retirement, Fidelity spokesman Steve Austin said.