NYSE Euronext and Germany's Deutsche Boerse AG will lead the ultra-competitive U.S. options trading industry once their merger is complete, data from clearinghouse OCC showed on Monday.

Overall, the nine U.S. options exchanges handled an average of 17.4 million contracts each day last month, up 32 percent from last year.

Deutsche Boerse's International Securities Exchange and NYSE's Amex and NYSE Arca venues together handled 40.3 percent of that trade, according to figures on the OCC website.

Last month NYSE and Deutsche Boerse shareholders approved the transatlantic merger, and the combination will overshadow all other options exchange operators.

Bragging rights for the No. 1 spot have in recent months gone to either CBOE Holdings Inc, which owns the oldest U.S. options exchange, or Nasdaq OMX Group, which operates two venues, PHLX and NOM.

CBOE, which also owns the electronic C2 market, handled 26.2 percent of all options contracts traded in July; Nasdaq handled 25.9 percent.

Traders say they expect NYSE and Deutsche Boerse to lose some of their collective volume once they complete the merger, as market participants spread their business among competitors.

But the large lead the three exchanges have over their nearest rivals suggests they will keep their collective top spot for some time to come, analysts have said.

The merger still needs the approval of regulators, which in Europe may require a review lasting through the end of the year.

Deutsche Boerse is buying NYSE Euronext for about $9 billion.

A specialized trading strategy linked to bets on stock dividends made up 4.2 percent of U.S. volume in July, ISE said in a separate report. A great deal of the volume in Nasdaq's PHLX venue comes from dividend trades.

ISE and CBOE say these dividend trades as a trading practice that distorts real market trends, and say their true shares of the market are higher if the trades are excluded.

(Reporting by Ann Saphir and Doris Frankel; Editing by Lisa Von Ahn, Bernard Orr)