Shares in On Assignment Inc. surged more than 6 percent early Friday after the staffing firm reported a plunge in fourth quarter earnings but issued strong first-quarter guidance.

On Assignment reported a 64 percent drop in fourth net income of $2.22 million (6 cents per share), which came in below the 8 cents per share that analysts polled by Thomson Financial were expecting. Net income a year earlier was $6.13 million, or 20 cents a share.

Revenue for the Calabasas-based company surged 99 percent to $152 million, exceeding analysts’ expectation of $147 million.

The company said that profit was hit by one-time charges such as severance packages, net interest charges and a considerably higher tax rate for the quarter ending Dec. 31.

The company added that it sees first-quarter net earnings between 6 cents and 10 cents per share on revenue of $147 million to $150 million. Wall Street has been predicting 8 cents per share profit on revenue of $147 million.

Shares in On Assignment gained 6.4 percent to $5.35 in early trading Friday on the Nasdaq.