SOUTH PORTLAND – WEX Inc., formerly known as Wright Express, posted better than expected fourth-quarter earnings but forecast future earnings below Wall Street’s expectations.

The credit card processing company’s shares fell 5.5 percent Wednesday to close at $74.46 on the New York Stock Exchange. Before Wednesday’s selloff, shares of WEX had gained about 34 percent over the past 12 months.

For the fourth quarter of 2012, WEX said net income totaled $29.1 million, 74 cents a share, down from $32.8 million, 84 cents a share, for the same period a year ago.

Adjusted earnings increased 9 percent to $41.8 million, $1.07 per share, from $38.4 million, 98 cents per share. Wall Street analysts, who track the adjusted earnings results, expected WEX to earn $1.06 a share.

Revenues increased 21 percent, to $169 million, topping analysts’ expectations of $164.4 million.

WEX forecast earnings to be below analysts’ forecasts for the first quarter and for 2013.

For the first quarter of 2013, WEX expects revenue to be in the range of $158 million to $165 million and adjusted net income to be in the range of $34 million, 89 cents a share, to $37 million, 96 cents a share. Analysts expect WEX to earn $1.08 a share on revenues of $163.86 million.

For the full year 2013, the company expects revenue of $721 million to $741 million. Adjusted net income will be in the range of $168 million, $4.30 a share, to $176 million, $4.50 a share. Analysts expect it to earn $4.86 on revenues of $716.04 million.

WEX said it expects to make significant investments to expand its business for virtual credit cards and prepaid payroll cards. The company expects to expand its virtual online travel business for hotels in markets such as Southeast Asia.

Virtual cards provide customers with 16-digit card numbers delivered to their computer screens. The accounts are prepaid with credit cards or debit cards.

“As we look to the upcoming year, there are a number of emerging opportunities across our business to drive our future growth, including global prospects for our successful virtual card product. Given our track record of targeting investments to yield strong performance, we plan to accelerate the level and timing of our strategic investments to maximize the potential of our businesses,” said Michael Dubyak, WEX’s chairman, president and chief executive officer.

WEX has grown through a series of acquisitions, including the recent $369 million deal to buy fuel-card company Fleet One from private-equity firms. Other recent deals include buying 51 percent of UNIK SA, a Brazilian provider of payroll cards, for about $21.9 million, as well as acquiring CorporatePay, a London-based provider of corporate prepaid cards for the travel industry, for about $27.5 million in cash.

WEX, which has been exploring moving its headquarters within Maine, said it has not made a decision yet on a new location. The company employs about 1,300 people worldwide.

Jessica Hall can be contacted at 791-6316 or at:

[email protected]