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.

Stocks plunged today on global concerns about emerging market currencies and weak economic data from China. All three major indexes fell throughout the course of the day, finishing down 2% or more as the Dow Jones Industrial Average (^DJI 0.41%) fell 318 points, or 2%. Investors also seemed to be nervous about next week's Federal Reserve Open Market Committee meeting, when many analysts expect the central bank could take the next step in its stimulus taper.

Fears of the taper and a weak manufacturing report in China led to a currency sell-off in countries as varied as Turkey, Argentina, and Ukraine. The Argentine peso, for example, fell 15% against the dollar, and the Turkish lira hit a record low as insurance against a Turkish default spiked to an 18-month high. A similar drop in emerging-market stocks occurred last June when the Federal Reserve first indicated that it would reduce its $85-billion monthly bond-buying program. The reaction is a reminder that the Fed's quantitative easing program was responsible for propping up not just U.S. stocks, but economies around the world as the rock-bottom treasury rates have made borrowing easier in international markets, as well.

Among Dow stocks reporting earnings today was Procter & Gamble (PG 0.65%), which finished as one of just three Dow stocks in the green, gaining 1.2%. The consumer goods giant posted earnings of $1.21 a share, beating estimates by $0.01, while revenue inched up 0.5%, to $22.28, just shy of the consensus at $22.36 billion. Organic sales were up 3% as newly returned Chairman A.G. Lafley said results were "as expected." Lafley was also optimistic about the second half of the year, saying, "We expect strong earnings growth, moderating headwinds from foreign exchange, and productivity savings." P&G maintained its guidance, saying it expects organic sales of growth 3%-4% and earnings-per-share growth of 5%-7%. Based on the market's reaction, investors were pleased with the mild earnings beat as P&G is a steady-earning, dividend-paying defensive stock that long-term investors can count on.

Also moving higher on earnings was Starbucks (SBUX 0.54%), which finished up 2.2% after posting its quarterly report last night. The coffee connoisseur posted a per-share profit of $0.71, a 25% increase, on expectations of $0.69 as sales improved nearly 12%, to $4.2 billion. Comparable sales were up 5% as CEO Howard Schultz said the company's results were especially impressive given the weak holiday sales reported by many retailers. He went on to explain that the company's "unique combination of physical and digital sales" positions it to thrive in a changing retail environment. Schultz's argument, and the solid quarter, is further evidence of Starbucks' potential for long-term growth.