Executives at Piper Jaffray Cos., the oldest and biggest investment bank in Minneapolis, decided a few years ago they needed to expand their actual investment bank.

Last week, that drive climaxed with the company’s biggest acquisition, one that will lead to its first name change in decades. Piper Jaffray will become Piper Sandler Cos. early next year when it completes the $485 million purchase of Sandler O’Neill and Partners, a boutique investment bank in New York that is a leading adviser in the financial-services industry.

The deal comes as investment banks around the world over the past year have slashed jobs amid seesawing markets, slowing economies and growing demand by both consumers and institutions for lower-fee investments that erode revenue and profits at such firms. Revenue at many investment banks, including Piper Jaffray, fell last year.

The purchase of Sandler O’Neill jolted Piper Jaffray investors and employees by signaling the firm is focused on growth amid the broader industry’s volatility. The company’s shares fell Tuesday, the day the news was announced, as tends to happen with acquiring companies. But they recovered the next day and finished the week up about 2.4%.

“We didn’t do this acquisition for consolidation or cost savings,” Chad Abraham, Piper Jaffray’s chief executive, said in an interview last week. “We’re focused on driving growth. That’s good for our employees, our clients and shareholders.”

The company for many years focused on providing investment-banking services — chiefly capital raising and mergers and acquisition advising — to clients in the health care, technology, consumer products and industrials sectors. In an assessment about five years ago, executives realized they were reaching only about half of the firms in the S&P 500 and, most notably, were missing the sizable energy and financial services sectors.

“Without energy and financials, we were missing a big chunk of the market,” Abraham said.

To reach out to energy-industry clients, Piper Jaffray in 2015 bought Simmons & Co. International, a specialist in the sector. To enter the financial-services sector, it bought River Branch Holdings, a boutique investment firm in Chicago, and hired five veteran investment bankers from Sterne Agee of Boston.

But even with those moves, financial services accounted for well under 10% of Piper Jaffray’s investment-banking mix. “It was going fine. It would have just taken many, many years to become the market leader,” Abraham said.

Sandler O’Neill over the last decade has advised more deals in the financial-services sector than anyone on Wall Street. In value, those deals ranked No. 3 after giants Morgan Stanley and J.P. Morgan Securities. The firm’s co-founder and lead partner, Jimmy Dunne, has a reputation as one of the nation’s top advisers on bank deals.

In recent years, bank consolidation has quickened slightly as, like other companies, they deal with the rising costs associated with new technology and regulations. Even with a deal pace of 200 to 300 mergers a year, there are still more than 5,000 banks in the U.S. and thousands more insurance, financial tech, mortgage, property and related firms.

“One could certainly see the pace of consolidation accelerate. But frankly it’s been pretty strong for the past several years,” Abraham said. “We’re not really banking on that accelerating. We’re just banking on that pace continuing.”

When the Sandler deal is complete, Piper Jaffray executives forecast the firm’s investment-banking revenue jumping to about $750 million annually from about $500 million. Its outreach to financial services firms will account for about one-third of that.

The company’s overall revenue, which also includes its sales and trading business and services for institutions, will climb to about $1.1 billion. Last year, it was $784 million.

Piper Jaffray has also made additions on the other side of the business. For instance, in 2015, it added to its municipal bonds business with the purchase of BMO Capital Markets GKST Inc. And it has beefed up its equity-research staff to mirror the growing reach of its investment banking side. With Sandler, Piper’s research coverage will grow to 850 companies from about 650.

“We have made sure when we’re approaching our institutional-brokerage business, or sales and trading businesses, that we are aligned with the investment banking business,” Debbra Schoneman, the firm’s president, said. “They aren’t really separate businesses.”

Of the $485 million deal, about $135 million is Piper Jaffray shares that offered as incentives to retain Sandler O’Neill employees. When complete, Sandler O’Neill employees will own about 16% of the ongoing Piper Sandler.

Such arrangements are common in business where the main asset is people, their knowledge and relationships. Abraham said leaders of the two firms have spent years getting to know each other and saw a cultural fit in the long-term continuity of employees that both have achieved.

“We think we have a platform that allows [Sandler O’Neill] to serve their clients. In the long term, that’s a lot more important than any sort of restrictions you would put on people,” Abraham said referring to the retention incentives. “In a people business; they have to want to work for you.”