Three restaurant stocks - Panera (PNRA), Darden (DRI), and Cracker Barrel (CBRL) - were downgraded by research firms today. Analysts expressed concerns about the stocks' valuations following their recent rally.

PANERA: Although Panera has a number of positive catalysts that should enable its comparative sales to stay strong going forward, it may not be able to beat the Street's current outlook by large amounts, wrote Wedbush analyst Nick Setyan. The company's new initiatives should boost its sales going forward, and it is launching delivery services which could increase its comp sales by up to two percentage points, the analyst stated. However, the company will probably have to invest in technology and labor next year, limiting its ability to beat consensus estimates, Setyan believes. Noting that Panera's current valuation is 20% above its peer average, the analyst wrote that he does not expect the stock's multiple to rise unless analysts' comp sales and profit estimates for it increase. He downgraded the stock to Neutral from Buy but kept a $220 price target on the name.

DARDEN: The company is continuing to outperform its casual dining peers as Olive Garden's turnaround continues, wrote Maxim analyst Stephen Anderson. Moreover, the company's margins can rise further as labor regulations ease, and it's building new, higher end restaurants, which should boost its revenue, Anderson believes. However, noting that the stock had risen 23% since early October, the analyst contended that the shares reflect all of these positive catalysts. He downgraded his rating on Darden to Hold from Buy and kept a $74 price target on the name.

CRACKER BARREL: Cracker Barrel's comparable restaurant sales should rise at least 2% in its January quarter, and its profits should increase at least 15% through fiscal 2018, driven by the strong sales and "aggressive cost controls," according to Maxim's Anderson. However, the analyst thinks that the stock, which has risen nearly 30% since early October, reflects these positive catalysts. He downgraded the shares to Hold from Buy but kept a $170 price target on the name.

PRICE ACTION: In morning trading, Panera fell 2% to $213, Darden slid 1.25% to $74, and Cracker Barrel lost nearly 2% to about $161 per share.