European stocks dropped, paring their biggest monthly gain since July 2009, as some investors remain reluctant to buy equities before the euro area’s leaders explain how they will fund their expanded bailout facility. The G-20 leaders convene on Nov. 3-4 in Cannes, France, a week after the euro area’s authorities pledged to magnify the capacity of their rescue fund to 1 trillion euros ($1.4 trillion). The euro area has already sought financial help from China and cooperation from the International Monetary Fund.

National benchmark indexes declined in all 18 western- European markets. The U.K.’s FTSE 100 Index slid 2.8 percent, while France’s CAC 40 Index and Germany’s DAX Index both retreated 3.2 percent.

Vestas slumped 24 percent to 84.35 kroner for its biggest slide since 2002. The wind-turbine maker predicted revenue of 6.4 billion euros in 2011, down from the 7 billion euros it had forecast in August. Vestas said its 2011 Ebit margin will decline to 4 percent. The company projected a margin of 7 percent in August. Vestas said further delays at the facility remain possible. Gamesa Corp. Tecnologica SA, the Spanish wind-turbine maker, plunged 9.6 percent to 3.52 euros.

Banks were among the worst performers of the 19 industry groups on the Stoxx 600. HSBC lost 3.6 percent to 544.9 pence. BNP Paribas SA sank 9.6 percent to 32.85 euros. UniCredit SpA slipped 5.7 percent to 84.8 euro cents as La Stampa reported that Italy’s largest bank plans to raise 6 billion euros to 8 billion euros. The newspaper didn’t say where it got the information.

Rio Tinto, the world’s second-biggest mining company, lost 6.5 percent to 3,385 pence. BHP Billiton Ltd., the world’s largest, declined 6.4 percent to 1,967.5 pence. Copper, nickel and tin prices slumped on the London Metals Exchange.

Homeserve Plc tumbled 28 percent to 350 pence for the biggest slump on the Stoxx 600 after the U.K.-based emergency- repair service provider suspended all telephone sales and marketing because a review showed sales processes didn’t meet standards.

TNT Express NV rallied 5 percent to 6.17 euros as Europe’s second-largest express-delivery service posted an unexpected third-quarter profit after increasing prices in Europe and Asia.