NEW YORK—While sales for the 10 largest retailers on the VM Top 50 list for 2011 increased by 6 percent to an estimated $6,819.2 million, their share of the total sales for the Top 50 dropped 1 percent to 85.9 percent. The mass merchants’ share of Top 50 sales picked up half a percent, which increased from 31.2 percent to 31.7 percent, with their total estimated 2011 sales growing 8.2 percent to $2,519.7 million.