Big retailers including Costco Wholesale, Macy’s, Target, and Kohl’s reported June sales on Thursday that failed to meet estimates. Some retailers even changed their earnings forecasts as a result. As the back-to-school season and the holidays get closer, a rotten retail stock could start to stink. Here’s what analysts are looking out for.

Costco reported a 3 percent increase in same-store sales, falling below estimates of 3.7 percent. “It’s estimated that 100 basis points of Costco’s June (same-store sales) was impacted by the shift of the July 4 holiday,” Dana Telsey of CEO of Telsey Advisory Group told CNBC, citing the mid-week holiday as one of three factors contributing to June’s same-store sales decline.

While big box retailers such asTarget and Costco reported disappointing sales, Wal-Mart Stores hit a new 52-week high on Thursday. Telsey said Wal-Mart’s 2.6 percent increase last quarter suggests that it is likely taking share from some of its big box competitors. She expects Wal-Mart to continue to gain share moving forward.

An additional factor that likely swayed June same-store sales is weather. “The fact that it is warmer, they cleared out goods potentially earlier than expected,” Telsey said, noting that it is possible that the weather shifted sales to earlier months .

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