Certify, a Portland company that develops expense management software, has been acquired by a California-based investment group.

K1 Investment Management, an investment firm focused on global software companies, purchased Certify and three other expense software companies for $125 million. The deal creates one company with more than 7,500 customers that use the specialized software to reduce overhead associated with managing employee time, travel and expenses. The combined company is positioned just behind SAP Concur, the largest expense management software company, according to a release announcing the acquisition.

“This deal is all about bringing the best expense management products to the most users everywhere in the world,” said Robert Neveu in a statement. He founded Certify in 2008 and is the company’s CEO. “We’re now in a much stronger position to develop products and serve customers in the U.S., Canada and internationally. I would expect us to continue growing organically and through acquisition as we move to overtake Concur as the world’s largest expense management software vendor.”

Neveu said Certify will maintain its Portland operation and the 90 people working for it.

The other companies acquired in the transaction are Nexonia, ExpenseWatch and Tallie.

The market for expense management software is expected to grow to $2.46 billion by 2020, according to K1. Neveu said Certify has been growing at a rate of 50 percent annually. It is part of Portland’s large payment processing cluster, which includes Wex, CashStar, Blue Tarp Financial and others.