That big drop in shares of Green Mountain Coffee Roasters (GMCR) Thursday? Blame it squarely on Starbucks (SBUX), which announced a very competitive price for its own coffee maker hitting stores next month.

Starbucks is already selling the Verismo maker on its own site. The machines start at $199 for a high-pressure brewing system that includes a milk steamer for DIY lattes and cappucinos (a larger version is $399). The machines use Starbucks' specialty coffee packs, which cost $12 for a pack of 12 coffee pods and $13 for a pack of eight espresso pods and eight milk pods.

Starting next month, the Verismo will be available at Macy's (M), Williams-Sonoma (WSM) and Starbucks' own stores. Starbucks is clearly positioning the Verismo to be the "it" gift of the holiday season.

Obviously, investors are concerned about what this will mean for Green Mountain, which became a stock market darling on the success of its Keurig home coffee brewers. Starbucks has maintained that its machine, made by Germany's Krueger GmbH & Co., is different from Green Mountain's brewers because the Starbucks machine is pressurized and can make espresso drinks.

But the Starbucks machine also brews regular coffee, which is very much in Green Mountain's territory. Green Mountain has an estimated 90% of the U.S. single-cup market, The Wall Street Journal reports. Green Mountain is developing its own single-cup espresso machine.

There is room for both companies and more. Green Mountain says its Keurig machines are only in about 11.5 million U.S. homes, the Journal reports. The company hopes its machines eventually end up in 35 million.

Green Mountain shares fell more than 8% Thursday to $28.18 as word of Verismo's pricing emerged. Starbucks shares rose nearly 2% to $51.02. Green Mountain shares have fallen 37% this year, while Starbucks shares have risen nearly 11%.

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