Stocks are broadly lower today as the unofficial kickoff to earnings season is a mere hours away, with economic bellwether Alcoa (AA) set to report after the closing bell -- click here for a preview of Alcoa's earnings. Although analysts expect earnings to grow for most blue chip companies, the growth is slated to be modest and significantly lower than previously forecast. Estimates peg the figure for the S&P 500 at roughly 3% on a year-over-year basis. In light of the anticipation, the Dow Jones Industrial Average (^DJI 0.56%) is trading down by 63 points, or 0.47%.

In terms of individual stocks, shares of Yum! Brands (YUM 0.46%), the proprietor of the KFC, Taco Bell, and Pizza Hut brands, are down more than 4.5% in midday trading. The move comes after the fast-food chain announced that same-store sales in China, its most important market, will fall more than expected. The company now expects the figure to be down by 6% compared to the previously announced estimate of 4%. The lagging sales follow the company's admission last month that it's "cooperating fully with the Chinese government's review of two poultry suppliers who provided chicken with unapproved levels of antibiotics to KFC."

Shares of GameStop (GME 1.07%) are also trailing the market today, down by 6.5% at the time of writing, making it the morning's worst-performing stock on the S&P 500. Earlier today, the video game retailer released same-store sales figures for the 2012 holiday season. Total sales for the period came in at $2.88 billion, a 4.6% decrease from the 2011 holiday season. On a year-over-year basis, sales at stores open at least one year fell by 4.4% globally and by 3.5% in the United States. According to GameStop's chief executive officer, Paul Raines: "GameStop experienced mixed results during the holiday selling period. ... As a result, GameStop expects its fourth quarter 2012 earnings per share results to be at the low end of its current guidance range."

Another stock struggling today is Colorado mining company Molycorp (NYSE: MCP), which is currently down 2.6%. Because there isn't any negative news out about the rare-earth mining company, many analysts believe that traders are simply booking profits after yesterday's double-digit gains. The stock closed higher yesterday by nearly 12% after riding a "minor fervor ... for rare-earth firms," as Barron's put it. According to an analyst cited yesterday in the Barron's article"[Molycorp is] ramping up production at a new Mountain Pass, Calif. mine, and China -- the world's biggest producer of these metals, like molybendum and titanium -- is closing down some mines."

Heading higher, alternatively, are shares of Star Scientific (NASDAQ: STSI). As my colleague Dan Caplinger noted earlier today, shares in the company are soaring in the wake of "positive results from a human thyroid study that looked at the impact of its anatabine dietary supplement, Anatabloc." Suffice it to say, many analysts expect sales of the supplement to climb if the results can be replicated more broadly.

How to beat bad earnings
At the end of the day, the world's greatest investors don't get hung up on one particular earnings season over another, because they buy great companies and hold them for years, if not decades, to come. As Warren Buffett has famously said, the best time to sell a stock is never.