This excerpt taken from the NDAQ 10-Q filed Nov 7, 2008.
Our operating results may be adversely impacted by global economic uncertainties.
The recent shortage of liquidity and credit combined with volatility and weakness in global markets could lead to a worldwide economic recession. Since trading volume is significantly affected by economic, political and market conditions and the overall level of investor confidence, a prolonged slowdown in economic activity caused by a recession may reduce trading volumes across our markets. Because a significant percentage of our revenues is tied directly to the volume of securities traded on our markets, it is likely that a general decline in trading volumes would lower revenues and may adversely affect our operating results. In addition, worsening economic conditions or a prolonged or recurring recession may reduce demand for our other products and services, further negatively affecting our financial condition.