A number of coal stocks are declining after BMO Capital stock analyst Meredith Bandy downgraded two companies in the sector. Bandy downgraded coal miners Peabody Energy (BTU) and Walter Energy (WLT) to Market Perform from Outperform, as she believes that both companies' profit margins are likely to drop in the future. Moreover, both companies have relatively high debt levels and high stock valuations, she added. In mid-morning trading, Peabody Energy declined 2% to $21.50, while Walter Energy slumped 3% to $30.60. Other coal mining companies also fell, with Alpha Natural Resources (ANR) slumping 3.5% to $8.25, Arch Coal (ACI) giving back 1.7% to $5.25, and Alliance Resource Partners (ARLP) losing 1% to $61.75.