This excerpt taken from the NDAQ 8-K filed Feb 20, 2008.
Nasdaq and OMX must adapt to significant competition in their listing businesses.
Nasdaq and OMX must adapt to significant competition in their respective listing businesses from other exchanges. Historically, the NYSE has been our largest competitor, and we have competed with the NYSE primarily for listings of larger domestic and international companies. OMX faces competition from various European exchanges for new secondary listings. In addition, on occasion, issuers may transfer their listings from Nasdaq and OMX to other venues. While the reduction in initial listings or the loss of one or more large issuers could decrease the combined companys listing revenues, it could cause an even more significant decrease in revenues from the quoting, reporting and trading of those issuers securities.