We performed a screening of mid-cap ETFs, defined as having Assets Under Management (AUM) between $400 million and $2 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 J.P. Morgan Alerian MLP Index ETN (NYSEARCA: AMJ) AMJ was down 0.75% on the week. The J.P. Morgan Alerian MLP Index ETN offers exposure to the energy MLP sector. MLPs are an attractive investment because t