Short sellers just haven't learned their lesson from Chipotle Mexican Grill ( CMG). Shares of the $13 billion fast-casual restaurant chain have rallied more than 43% since the calendar flipped over to January, basically guaranteeing that anyone who bet against this perennially-hated stock this year is getting shellacked. But CMG's short interest ratio is still up at 10.61. Chipotle operates more than 1,500 stores across the U.S. and Canada, with a smaller presence in the U.K. and France. While Chipotle's operations across the pond provide a solid testbed for a couple of exciting markets, the real growth story is still centered on North America right now. Chipotle estimates that it can still double its store count here at home before the market starts to get saturated, a fact that leaves a lot of room open overhead for growth. Despite stiff competition, Chipotle continues to offer a value proposition that customers want -- and its higher-quality positioning means that it's able to collect thick margins for its trouble. Just as important as how fast Chipotle is growing is how it's paying for that growth. To date, Chipotle has almost exclusively used cash from operations to finance its new stores, providing the firm with a debt-free balance sheet and nearly $500 million in cash. That lack of leverage means that CMG can weather the next economic hiccup better than most restaurant names. It also means that we could easily see a short squeeze in shares. Keep an eye on this one. To see these short squeezes in action, check out this week's Short Squeezes portfolio on Stockpickr. -- Written by Jonas Elmerraji in Baltimore.