European stocks tumbled to a two- year low as the Federal Reserve signaled “significant downside risks” to the world’s largest economy and Moody’s Investors Service downgraded three U.S. banks.

National benchmark indexes retreated in all of the 18 western European markets. Germany’s DAX Index declined 5 percent and France’s CAC 40 dropped 5.3 percent. The U.K.’s FTSE 100 slid 4.7 percent, the most since March 2009.

Logitech International SA (LOGN), the world’s biggest maker of computer mice, plunged 12 percent after cutting its forecasts for the second time in two months. Rio Tinto Group, the world’s second-largest mining company, sank the most in more than two years as copper fell for a fifth day. LVMH Moet Hennessy Louis Vuitton SA (MC) and Burberry Group Plc (BRBY) led luxury stocks lower.