LEWISTON – Merrill Lynch is the latest tenant to sign on to the Business Service Center at KeyBank Plaza, bringing the 2-year-old center to about 75 percent occupancy.

“I think it’s pretty remarkable so soon after the building has been completed,” said Paul Badeau, marketing director for the Lewiston-Auburn Economic Growth Council, which has been pursuing tenants for the building. “We have a couple of possibilities we’re working with now that might complete the building.”

A ribbon-cutting ceremony for Merrill Lynch will be paired with an open house to celebrate the resurgence of the city’s Southern Gateway area. New Gateway neighbors, including Northeast Bank, VIP Auto, Andover College, Oxford Networks, Public Theatre and the Business Service Center will offer tours and refreshments from 3 to 5 p.m. Thursday, Oct. 16.

Merrill Lynch, the financial services firm that recently merged with Bank of America, took 2,500 square feet of the former Pontiac Building. Seven staff are working from the third-floor renovated space, which features warm woods, exposed brick and views of downtown Lewiston.

The space allows for additional staff to be hired, said Marc Pellerin, head of the local office. The company’s former office was on Park Street.

There are about 2,000 square feet of space left on the third floor and 2,100 square feet of unoccupied space on the second floor adjacent to LPS Capital Markets, which moved in earlier this year.

The redevelopment of the 100-year-old grocer and car dealership building was a $2 million project, the culmination of a dream harbored by the LAEGC’s Lucien Gosselin and Chip Morrison of the Chamber of Commerce to bring business-assistance organizations under one roof. In January 2007, the chamber moved into its first-floor suite while the LAEGC took the fourth floor, sharing the penthouse view with Maine International Trade Center, Coastal Enterprises Inc., the Auburn and Lewiston development corporations, and PTAC, the federal contract assistance program.

The organizations are paying for their condo space through budgets and subleases.

Free parking will be available during the Gateway open house at the Public Theatre lot and the municipal garage. The chamber will hold its Business After Hours networking social following the open house at the Public Theatre from 5 to 7 p.m.