We performed a screening of medium-cap ETFs, defined as having Assets Under Management (AUM) between $2 billion and $10 billion - to determine what funds had the largest positive and negative returns on the week, according to data from etfdb.com. Only non-leveraged funds were considered. Winners Vanguard Energy ETF (NYSEARCA: VDE) VDE was down 3.36% on the week. The Vanguard Energy ETF is tied to the MSCI US Investable Market Energy 25/50 Index, offering broad exposure to the US energy industry.