A few of us here at the Fool were abuzz this morning looking at all of the new comparable-store sales numbers coming out. The retailers reporting range from Motley Fool Stock Advisor recommendation The Gap (NYSE:GPS) to Ross Stores (NASDAQ:ROST) to BJ'sWholesale Club (NYSE:BJ), and the numbers have been pretty positive for the month, though BJ's and Ross Stores reduced guidance for the quarter.

At the other end of the spectrum on same-store sales increases and stock-price performance today is none other than Guess? (NYSE:GES). It's been an interesting few months for the company best known for its denim wares. Its first-quarter earnings report was generally solid: Revenues rose by more than 40%, and the company benefited from some timing issues, but April same-store sales were down slightly.

In May, the company reversed the negative same-store sales numbers, but then back in June, an analyst downgrade whacked the company's share price. I normally wouldn't comment on the timing of an analyst shift, but the downgrade from Pacific Growth Equities looks a bit more strange now, in light of today's report from Guess? that same-store sales increased by 11% in June.

As a resurgent brand, Guess? has put in an impressive performance from a sales perspective, but the real story driving the performance is the operational improvements of the past few years. With older, underperforming stores closed and the company refocused on domestic operations, margins have been trending upward in recent years. Guess? has also been focusing on improving and automating its inventory-management processes, a project that continues this year.

Today's 10% pop is pricing in a number of these improvements. However, if the company can continue its current growth without sacrificing its lean inventory position and solid balance sheet, there's good reason to believe that prices just may surpass the levels last seen in 2000.

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Nathan Parmelee beneficially owns shares of The Gap but has no financial interest in any of the other companies mentioned. You can view his profile here. The Motley Fool has an ironclad disclosure policy.