Investors in Starbucks (SBUX) reacted negatively to the company's purchase of Bay Bread and its La Boulange bakery brand for $100 million, though Bernstein said in a note to investors that it sees the deal driving incremental traffic and comp increases over time. Shares of the coffee giant fell 3.75%, while Panera Bread (PNRA) traded 1.25% lower, with the move attributed to Starbucks' acquisition news.

Dollar General (DG) reported better-than-expected​ quarterly results on the top and bottom line and raised its full-year earnings view, but fears of dilution outweighed the positive sentiment about earnings as the company also filed to sell 25 million shares of common stock for holders. Dollar General's stock was down about 3% near noon.
 
Among the notable gainers Tuesday are Westport Innovations (WPRT), up over 18%, following its announcement of a deal with Caterpillar (CAT) to co-develop natural gas technology for off-road equipment that Craig-Hallum called a validation of Westport's technology, and Groupon (GRPN), up more than 7%, as Benchmark Co. said that the expiration of the company's IPO lock-up last Friday removed an overhang on the stock. Also higher were shares of Freescale Semiconductor (FSL), up about 8%, after naming Gregg Lowe, formerly of Texas Instruments (TXN), as its new president and CEO.

Noteworthy losers include Shuffle Master (SHFL), down almost 16%, following its report of earnings that were in line with consensus estimates, and Limelight Networks (LLNW), down over 12%, after Netflix (NFLX) announced that it would use its own Internet content delivery network. Jefferies said in a note to investors that Netflix accounts for 11% of Limelight's revenue.