The company bought oil rigs at low prices from Seahawk Drilling, another oil company with debt on the balance sheet, at a time when larger oil companies are spending cash to rebuild rigs, they say.

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It lacks the mammoth balance-sheet that oil firms maintain to manage the huge risks in oil exploration.

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Debris was tangled in the median's crossover barriers, including huge pieces of sheet metal, tree limbs and a giant oil drum.

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Maersk also benefits from a relatively strong balance sheet and its makeup as a conglomerate with a large oil and gas business that brings in comparatively stable earnings.

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