Boston Private Bank & Trust Co., which was established in 1987 and opened this office in Wellesley six years ago, is now opening new branches in Lexington and Hingham.

When Boston Private Bank & Trust Co. set out seven years ago to expand regionally with private banking offices, there was a goal to establish a presence in the northern, southern and western suburbs of Boston. The goal has been met, as the bank prepares to open two new branches: one in Hingham and the other in Lexington.

The Lexington branch is slated to open in September while the Hingham branch will open sometime in the fourth quarter this year.

The expansion into the two affluent communities in the Bay State is deliberate, according to Mark D. Thompson, Boston Private Bank & Trust chief executive officer. The bank has consistently expanded into towns that fit the bank’s wealth management model.

The institution usually looks to establish itself in towns where there is a concentration of affluent clients.

“They’ve done really well with their niche,” said George K. Darling, chief executive officer and founder of the Darling Consulting Group in Newburyport.

The institution established its first branch office in Wellesley six years ago and now has locations in Boston’s Back Bay, Jamaica Plain and Seaport District; Cambridge’s Kendall Square; and Newton. Established in 1987, Boston Private Bank offers deposit and cash management services, residential mortgages, investment management services and commercial banking for both individuals and businesses. The bank also provides commercial banking services to many of New England’s leading small and mid-sized corporations, according to its Web site.

Thompson said the Hingham branch represents the bank’s South Shore presence and he hopes it will reach customers in neighboring affluent towns, such as Cohasset and Norwell. Ultimately, there is a goal that the South Shore branch will be a “gateway to the Cape,” he noted.

Thompson added that there is a “tremendous” amount of wealth moving into the Hingham area, which is good for the bank’s investment management goals. Home prices in the area are also high, he said, making for good mortgage opportunities.

‘Compelling Demographics’

Meanwhile, the Lexington branch is expected to be a strong location because of its proximity to businesses in the Route 128 area, according to Thompson.

“It’s close to the venture capital market [in Waltham],” he said.

Venture capital firms already have been a strong client base for the bank.

“Venture capital is a great example,” Thompson said. “It [is] a great illustration of the type of clients we deal with.”

Retirees are also an important market, he said, because that particular group will be looking for investment management services in the near future.

“It will be a very attractive business,” Thompson said.

Thompson said the bank runs analysis on the demographics and other factors in a community before deciding to set up a branch. Median home prices and towns with a concentration of professional firms tend to be drivers for the bank. In the six years during which Boston Private Bank has been in Wellesley, it has garnered the No. 2 market share in the town, Thompson said.

“If you look at the median income [of people living in towns where the bank operates], they are all significantly above average,” Darling said.

The bank offers four core services to its client base: deposit management, which includes checking accounts and short-term cash management; residential mortgage financing; commercial lending; and investment management and trust services.

“Our advantage as a private bank and wealth management company is we really feel we can offer a very high level of personal service in addition to expertise we have with those four core services,” Thompson said.

Darling said the bank strives to offer “superb” service in order to attract funding for its growth plans.

In an age when many bank customers are using the Internet to check their bank accounts and even pay bills, Thompson said 30 percent of Boston Private Bank & Trust’s customers use the Internet for banking.

“We let the clients decide what channel of communication they’re most comfortable [with],” Thompson said.

Many of the customers interact with the bank’s staff to conduct their business.

“Our clients really do appreciate and value the relationships they have with private bankers,” Thompson said.

The relationships built with customers have been part of the bank’s strategy to grow. As a customer’s wealth grows, Thompson said, the bank can discuss investment strategies.

“We have a strong investment expertise,” Thompson said.

For customers with businesses, as their company expands, the bank can provide loans.

“Our sales strategy is geared toward new wealth creation,” Thompson said.

Over the past year, the bank’s assets have grown 21 percent and the institution has had a five-year growth rate of 28 percent. Much of the bank’s business comes from referrals; Thompson said 70 percent of new business is derived from referrals from existing clients.

Despite its niche, Boston Private Bank & Trust competes with all bank sizes, according to Thompson.

“We can compete with large institutions [as well as community banks],” Thompson said.

Darling said Boston Private competes with the private banking departments of larger institutions, such as the North Carolina-based giants Bank of America and Wachovia Corp.

Working with high-net-worth clients isn’t all Boston Private Bank & Trust does. With an “Outstanding” Community Reinvestment Act rating, the bank has a strong focus on affordable housing and economic development.

The bank is the No. 1 lender of low-income loans per asset class in Boston. Through its Community Homeowner and Accessible Banking programs, Boston Private Bank & Trust provides financing for affordable housing, economic development and small businesses, according to its Web site.

In the coming months, the bank expects to open another branch, which will be located on Boston’s North Shore. That move comes as the number of affluent households in the United States is only expected to increase. According to Thompson, Massachusetts ranks No. 6 in the country with 120,000 affluent households – a figure expected to balloon to 840,000 in the next 20 years.

“It’s great, compelling demographics,” Thompson said.