Smaller retailers can feel smug knowing megastore chain Wal-Mart suffered from lower-than-expected sales and traffic this past holiday season too. The company issued revised fourth quarter guidance on Friday, with earnings expected at or below the low-end of previous guidance between $1.60 and $1.70 a share. Full-year earnings are expected at the low-end of $5.11 to $5.21 a share. Wal-Mart expects slightly negative comparable sales growth for both its namesake store and membership-only Sam's Club. Previous guidance had Wal-Mart with flat comps and Sam's Club with growth as high as 2%.