Rehabilitation services company RehabCare Group Inc. said its second-quarter earnings more than doubled, as revenue surged due to an acquisition.

But the St. Louis company's performance fell short of analyst expectations, and the stock skidded in Wednesday afternoon trading.

RehabCare said late Tuesday it earned $14.7 million, or 59 cents per share, in the three months that ended June 30. That compares to net income of $6.9 million, or 38 cents per share, in the same quarter of 2009.

Revenue climbed 63 percent to $334 million.

Analysts polled by Thomson Reuters expected, on average, earnings of 63 cents per share on $338.1 million in revenue.

RehabCare completed a $570 million acquisition of Triumph Healthcare, a long-term acute care hospital operator, last November. The company said Wednesday Triumph contributed $110.8 million toward its revenue total.

RehabCare also said second-quarter results were hurt by a $1.7 million pretax adjustment for estimated prior year cost report settlements at an inpatient rehabilitation facility.

The company also said total costs and expenses rose 57 percent to $302.7 million.

Shares of RehabCare fell $3.02, or 14 percent, to $18.65 in afternoon trading.