Hewitt Associates has entered into a definitive agreement to acquire EnnisKnupp, a US-based provider of investment advisory services.

The news comes just one week after Hewitt announced it would merge with the global consultancy arm of Aon Corporation in a transaction worth $2.9 billion.

Russ Fradin, chairman and chief executive officer of Hewitt Associates, said: "EnnisKnupp's advisory capabilities and client portfolio are a perfect complement to Hewitt's actuarial business and expertise in managing pension risk.

“Our commitment to be a top-tier global investment consulting player and the potential to combine forces with EnnisKnupp were also real positives for Aon in our proposed transaction."

Hewitt Investment Group (HIG), Hewitt's existing investment consulting practice in the US, specialises in advising defined contribution (DC), defined benefit (DB), endowment and foundation clients on investment management, pension risk and asset allocation solutions.

Currently, EnnisKnupp's 135 Chicago-based employees provide investment advisory services to 167 clients. HIG already serves 120 clients from offices in five major US cities.

Steve Cummings, president and chief executive officer of EnnisKnupp, added: "As institutional investing becomes increasingly complex, organisations are looking for an advisor that has global reach and solid experience across actuarial, pension risk, plan administration and investment consulting services.

"Together, we can meet the needs of a broader range of clients while staying true to our shared promise of exceptional client service with the highest levels of integrity and professionalism."

Financial terms of the agreement were not disclosed. The transaction, which is subject to customary closing conditions including regulatory approval, is expected to close during Hewitt's fiscal 2010 fourth quarter.

Read more details on the Hewitt-Aon merge