TULSA, Okla. (


) -- Even though oil prices have nearly doubled since March,

Exxon Mobil's

(XOM) - Get Report

stock has been lethargic. Shares of the oil giant have gained 14% since March 6, while those of rivals


(CVX) - Get Report



(BP) - Get Report

have jumped more than 35%.

As Exxon flounders, smaller firms are filling the gaps and rewarding investors.

Arena Resources

(ARD) - Get Report

, a small exploration and production company, has been quietly beating the pants off all three with a return of 89%.

Tulsa, Okla.-based Arena operates fields in Oklahoma, Texas, New Mexico and Kansas. Oil accounts for 91% of its revenue, while natural gas rounds out the remaining 9%.

Today, the company is expected to report third-quarter earnings that fell 61% to 27 cents a share from a year earlier on a 51% drop in revenue, which reflects the 30% slide in crude prices during the period.

However, third-quarter results won't reflect the recently added fourth drilling rig on its Fuhrman-Mascho site in Texas, which should increase the company's production and help it exploit rising oil prices. The company expects the rig to drill 10 wells by the end of the year.

Even without the new rig, Arena has shown strength in almost every measure that has been weak for the industry. Its 23% return on equity is impressive alone, but when compared to the negative 39% average of its peers, it's outstanding.

Arena boasts a balance sheet that's free of debt. It finances its operations with retained earnings and surplus capital, and boasts a quick ratio that's more than triple the industry average.

While low-cost debt financing could boost growth, the benefit would be marginal. The company has a cash balance of more than $68 million and enough cash flow to comfortably support its investments.

An operating margin of 66% versus the industry's 26% average shows Arena's efficiency, but its 40% net margin compared with peers' negative 24% highlights how its lack of debt boosts results. High debt has weighed down its competitors, while Arena has stayed nimble and profitable.

Arena is a good bet for those wary of the mediocre returns of some of the big oil players. Exxon's name might have cache, but Arena offers performance.

-- Reported by David MacDougall in Boston.

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Prior to joining TheStreet.com Ratings, David MacDougall was an analyst at Cambridge Associates, an investment consulting firm, where he worked with private equity and venture capital funds. He graduated cum laude from Northeastern University with a bachelor's degree in finance and is a Level III CFA candidate.