Vestas Wind Systems A/S, the world's biggest wind turbine maker, rose the most in two weeks in Copenhagen trading as investors who had borrowed the stock and sold it on bets it would decline repurchased the shares to cover their so-called short positions. Vestas jumped as much as 8.7 percent, the most since Feb. 3, making it today's biggest winner in the Copenhagen 20 Index. The stock advanced 1.6 kroner to 54.60 kroner at 9:40 a.m. in the Danish capital. The Aarhus, Denmark-based company has lost 68 percent of its market value over the past 12 months after cutting sales and profit forecasts.