The largest specialty insurance brokerage in the U.S. acquired a New York-based 401(k) investment and advisory firm, seeking to expand its presence in the Northeast.

Alliant Insurance Services, based in Newport Beach, Calif., bought Thesco Retirement Planning Services (TRPS), one of the nation’s largest 401(k) advisory and brokerage firms, according to the company.

Financial terms of the deal were not disclosed.

Most of the retirement plans managed by TRPS are in the defined-contribution plan category.

TRPS, which has offices in New York City, Long Island, and New Jersey, is headed by President John Cunningham, who has 20 years of 401(k) advisory experience and helped found the firm in 2001. TRPS was recognized in both 2010 and 2011 as a Top Ten 401(k) advisory firm by Plan Sponsor magazine and voted “Top 300 Most Influential Advisors” by The 401(k) Wire.

“The acquisition of TRPS is an outstanding strategic fit for Alliant that serves to significantly increase our company’s presence in the 401(k) marketplace in the Northeast,” said Tom Corbett, Alliant chairman and CEO, in a statement.

Cunningham said his company was “excited” to become part of Alliant, which provides property and casualty, workers’ compensation, employee benefits, surety, and financial products and services to 20,000 clients nationwide, including public entities, tribal nations, healthcare, energy, law firms, real estate, construction, and other industry groups.