Oil and natural gas company Arena Resources Inc. said Tuesday that its fourth-quarter profit fell 31 percent as costs and operating expenses more than doubled.

The results came in below Wall Street estimates and the company's stock dropped.

Arena said it earned $9.3 million, or 24 cents per share, in the quarter ended Dec. 31 compared with $13.6 million, or 35 cents per share, in the 2008 fourth quarter. Revenue increased to $42.4 million for the quarter, compared with $33 million in the year-ago quarter.

Costs and operating expenses totaled $27.7 million for the quarter compared with $11.9 million in the year-ago quarter.

Analysts surveyed by Thomson Reuters expected profit of 35 cents per share, on $41 million in revenue, for the most recent quarter.

Arena shares fell $4.92, or 11.5 percent, to $37.77 in midday trading Tuesday. The shares have traded between $18.96 and $45.72 over the past year.

For the year, Arena earned $42.3 million, or $1.09 per share, compared with $83.6 million, or $2.20 per share, in 2008. Revenue totaled $126.2 million in 2009, down from $208.9 million in 2008.

The company said proved reserves of oil and gas increased 5.5 percent over the year to 69.2 million barrels of oil equivalent.