CME Group , the biggest U.S. futures exchange operator, on Thursday said fourth-quarter profits rose sharply because of tax benefits and said it would institute a special annual dividend on top of its regular quarterly payout, which it also increased.

CME also said MF Global's bankruptcy caused a $30 million hit to fourth-quarter results.

The company, which operates the Chicago Mercantile Exchange, the Chicago Board of Trade and the New York Mercantile Exchange, posted a profit of $745.9 million, or $11.25 per share, compared with a year-earlier profit of $196.2 million, or $2.93 per share.

CME results included a $528 million benefit from an adjustment to the value of deferred tax liabilities. Excluding that and the MF Global losses, CME earned $3.55 per share in the period. Analysts polled by Thomson Reuters I/B/E/S expected earnings per share of $3.64.

Trading volume fell 2 percent from a year earlier, though average revenue per contract rose 4 percent to 81.1 cents from 77.9 cents in the third quarter and was flat from a year earlier. The firm cited higher volume in higher-priced commodity contracts.

(Reporting By Ben Berkowitz; Editing by Derek Caney)