From Morgan Stanley’s 10-Q, about the most succinct statement possible of the potential unintended consequences of the U.S. debt downgrade:
Concerns regarding downgrade of the U.S. credit rating and the sovereign debt crisis in Europe could have a material adverse effect on our business, financial condition and liquidity.
On August 5, 2011, Standard & Poor’s lowered its long term sovereign credit rating on the United States of America from AAA to AA+. While U.S. lawmakers reached agreement to raise the federal debt ceiling on August 2, 2011, the downgrade reflected Standard & Poor’s view that the fiscal consolidation plan within that agreement fell short of what would be necessary to stabilize the U.S. government’s medium term debt dynamics. This downgrade could have material adverse impacts on financial markets and economic conditions in the United States and throughout the world and, in turn, the market’s anticipation of these impacts could have a material adverse effect on our business, financial condition and liquidity. In particular, it could disrupt payment systems, money markets, long-term or short-term fixed income markets, foreign exchange markets, commodities markets and equity markets and adversely affect the cost and availability of funding and certain impacts, such as increased spreads in money market and other short term rates, have been experienced already as the market anticipated the downgrade. In addition, it could adversely affect our credit ratings, as well as those of our clients and/or counterparties and could require us to post additional collateral on loans collateralized by U.S. Treasury securities. Because of the unprecedented nature of negative credit rating actions with respect to U.S. government obligations, the ultimate impacts on global markets and our business, financial condition and liquidity are unpredictable and may not be immediately apparent.
via Form 10-Q.