* Nasdaq had 27.2 pct market share; CBOE had 26.6 pct
* ISE, ranked No. 4, says Nasdaq's figures "inflated"
* Trading at all U.S. options markets up 3.5 pct in Oct
By Ann Saphir
CHICAGO, Nov 1 (Reuters) - Nasdaq OMX Group's
But those bragging rights came under immediate fire from
Deutsche Boerse
More than a quarter of the 77.8 million contracts traded in October at Nasdaq's PHLX, formerly known as the Philadelphia Stock Exchange, were so-called dividend trades, ISE estimates released on Monday showed. The trades provide little economic value and pose a threat to market stability, ISE said.
Nasdaq, which gets almost no revenue from the trades, says they are legitimate and should not be treated differently. The exchange operator, which also runs the smaller NOM venue, handled 92.9 million contracts in October, or 27.2 percent of all U.S. stock and stock-index trades.
CBOE Holdings Inc, which launched its own second exchange
on Friday, handled 26.6 percent of all trading, while NYSE
Euronext
ISE trailed at No. 4 with just 18 percent of the total, highlighting concerns that its Frankfurt-based parent will be forced to write down a large chunk of the value of the New York-based options market.
Deutsche Boerse warned last week that such a write-off was likely, following an earlier charge taken a year ago. [ID:nLDE69R1LY]
ISE, the only major options-exchange operator to have just one venue, is considering starting its own second market to win back customers.
All nine U.S. options exchanges together handled 342 million contracts last month, up 3.5 percent from last year. (Reporting by Ann Saphir; editing by Gunna Dickson)