Investor fears drag down shares of exchange operators

As investors worry that troubled financial institutions will scale back on trading, which would hit exchanges' revenues, shares of exchange operators are dropping. The value of CME Group, for example, has fallen 43% this year. Nymex Holdings and IntercontinentalExchange are down 36% and 51%, respectively. The sell-offs, however, appear to be excessive compared with those of brokerages, which seem to announce massive write-downs each quarter.