Wright Express Corp., which processes fuel purchases for commercial automotive fleets and other credit card transactions, posted a 22 percent jump in adjusted first-quarter earnings as it expanded its fleet business and saw gains from its corporate charge-card product.

But the South Portland-based company’s stock price dropped about 5.8 percent Wednesday as it forecast second-quarter earnings below Wall Street’s expectations. The stock closed at $60.29, down $3.69.

For the first quarter of 2012, adjusted net income totaled $35.6 million, or 91 cents a share, up from $29.2 million, or 75 cents a share, from the same period a year ago. The quarterly earnings were slightly above Wall Street’s expectations of 90 cents a share, according to First Call.

Total revenue increased 17 percent, to $140.1 million, from $120.1 million for the first quarter last year, according to Wright Express, which has 600 employees in Maine and about 900 overall.

Besides processing fuel transactions, the company also helps customers capture and analyze detailed fuel and maintenance information.

Wright Express had growth in the construction, transportation and business services industries in the first quarter, said CEO Mike Dubyak.

For the second quarter, Wright Express forecast earnings in the range of 92 to 98 cents a share. That’s below Wall Street analysts’ average forecast of $1.08 a share, according to First Call. Wright Express expects second-quarter revenue to be in the range of $145 million to $150 million.

For the year, the company projects revenue in the range of $602 million to $617 million, with adjusted net income to be in the range of $160 million to $168 million, or $4.10 to $4.30 a share. Wall Street analysts expected full-year earnings of $4.27 a share.

Wright Express said its guidance is based on an assumed average U.S. retail fuel price of $3.93 per gallon, while the full-year guidance assumes a price of $3.72 per gallon.

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

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