Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

With a new era of Federal Reserve policy possibly in the air, Wall Street sold off on Tuesday as investors showed what they truly think about the possibility of a December taper. Given last week's exemplary jobs numbers, there's reason to believe the central bank could begin reining in its loose money policies as soon as next week. The benchmark S&P 500 Index (SNPINDEX:^GSPC) lost five points, or 0.3%, to end at 1,802 on Tuesday.

The $111 billion biotech behemoth Gilead Sciences (NASDAQ:GILD) was one of the index's most pronounced losers today, with shares shedding 3.2% in trading. The losses, which came on heavy volume, came as drug benefits manager Express Scripts expressed its willingness to examine competitors to Gilead's new hepatitis C treatment in an effort to bring down costs. Gilead's Sovaldi may be too expensive for Express Scripts to endorse for reimbursement if it goes to market for $1,000 a pill. 

Elsewhere, Starbucks (NASDAQ:SBUX) stock was feeling the hurt from high expectations on Tuesday, as shares tumbled 3%. Preliminary numbers from ITG Research put sales at company-owned stores around $2.8 billion in the current quarter, a figure that, if accurate, would fall slightly short of expectations. Starbucks stock has been on fire in 2013, gaining 44%. Obviously, growth is what's keeping this stock alive, and even though international expansion remains a big part of the story, the U.S. remains the company's biggest market and a vital part of its financial success. 

Oil and gas exploration company Newfield Exploration (NYSE:NFX) continued to see fallout from its production outlook for 2014, dropping 2.6% Tuesday. While Newfield sees liquids production growing by 20% a year over the next three years, that's apparently not enough growth for investors in the $3 billion energy company. Natural gas is a massive area of opportunity for investors in the U.S. energy renaissance, and competition is rather stiff, which means 20% a year isn't the best growth on the block

Fool contributor John Divine has no position in any stocks mentioned. You can follow him on Twitter @divinebizkid and on Motley Fool CAPS @TMFDivine.

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