Some Wal-mart express stores are closing, but not before doing some damage to local grocers. Until last year, independent grocers made up more than half of Chicago’s market. That changed as more Wal-Marts, Whole Foods and Targets came into the equation. Wal-mart announced that two of its express locations would soon close, but that’s such a small fraction of their footprint. And, along with the chains closing, an independent stalwart in the Lincoln Park neighborhood shuttered. Brigid Sweeney covers retail for Crain’s Chicago Business and she talks about the changing landscape for grocery stores.