Rivals NYSE Euronext and Nasdaq OMX Group both claim that to have listed the most global initial public offerings during the first quarter of 2013, while Thomson Reuters' data show the two exchange operators as tied.
The differences come down to arguments over how to account for or define initial public offerings.
In a statement on Thursday, Nasdaq said it had topped U.S. exchanges in IPOs with 18 listings, including Norwegian Cruise Line Holdings, communications company West Corp. and money transfer services provider Xoom Corp.
Nasdaq said the New York Stock Exchange, owned by NYSE Euronext, had just 16.
By its definition of IPO, Nasdaq said it includes real estate investment trusts, spin-offs and deals known as "best efforts," in which the underwriter does not firmly commit to selling shares.
In response, a NYSE spokeswoman emailed journalists to counter what it characterized as "incorrect data regarding the U.S. IPO market" contained in the Nasdaq statement.
The New York Stock Exchange operator said that by its method of measuring IPOs—which includes traditional IPOs, REITs and closed-end funds—it had 25 listings compared with 17 for Nasdaq. NYSE also said it relies on Dealogic and Ipreo for its data.
But the outcome of the battle this quarter may have ended without a clear win for either exchange.
According to Thomson Reuters data—which consider traditional IPOs, spin-offs and REITs, but not blank-check companies—both NYSE and Nasdaq ended the first quarter with 16 listings.
Traditionally, Nasdaq had a lock on technology company listings and NYSE on blue-chip stocks, but both have made inroads into each others' respective territories in recent years.
The turf war for marquee tech names heated up last year ahead of Facebook's long-awaited IPO, with the CEOs of both exchanges reportedly flying to California to woo the management of the social network.