SOUTH PORTLAND — Credit-card processing company WEX Inc., formerly known as Wright Express, was recognized by Forbes magazine as one of America’s 100 Best Small Companies for the fifth consecutive year.

WEX ranked as No. 20 on the 2012 list, up from No. 30 in 2011.

“This achievement reflects the dedication of our associates to our core company values – integrity, innovation and execution. It also reflects our strong commitment to investing in the development of valuable and innovative products and to delivering an exceptional customer experience to drive further success,” said Michael Dubyak, WEX chairman, president and CEO.

Forbes’ rankings of small businesses began in 1996 and reflect factors such as sales and earnings growth, as well as return on equity, at growing, publicly held companies.

WEX, which employs more than 1,200 people, has been on an acquisition spree, buying companies such as fuel-card company Fleet One, and CorporatePay, a London-based provider of corporate prepaid cards for the travel industry.

The company also has been evaluating options for its office space, but still aims to keep its headquarters in Maine.

View Forbes’ full list of “America’s 100 Best Small Companies” for 2012.