When it comes to the biggest companies in the world that are based in the United States, it's easy to dismiss the troubles brewing in the emerging markets. After all, blue-chip stocks such as Procter & Gamble (PG -0.10%), Coca-Cola (KO -0.14%), and PepsiCo (PEP -0.71%) are headquartered in the United States. Each of them is a world-class brand, and their products can be found in nearly every household in the nation. As a result, why should calamity in regions across the world have a material impact on their businesses?

However, when it comes to P&G, Coca-Cola, and PepsiCo, the truth is that they derive the majority of their revenue from international sales. In particular, they're doing more business in the emerging markets than ever before. That's why the carnage currently rippling through the stock market is closely tied to what's happening in the emerging markets.

American companies in name only
While it's true that P&G, Coca-Cola, and PepsiCo are symbols of the American capitalist spirit, it's also true that they derive the majority of their sales from outside the United States.

P&G's stable of world-class brands, including Crest toothpaste, Bounty paper towels, and Tide laundry detergent, can be found in more than 180 countries across the globe. In all, P&G holds 50 brands that represent more than 90% of its sales and profits. Half of these, known as the 25 billion-dollar brands, each generate at least $1 billion in annual sales. This success is due largely to strong growth in the emerging markets. P&G derived just 39% of its 2013 net sales from North America.

Coca-Cola's products are available in more than 200 countries. Its performance in North America was far exceeded by its performance across the world in recent quarters. For example, Coca-Cola Americas grew volumes by 1%, whereas Coca-Cola international increased volumes by 3% in both the third quarter and year to date.

Likewise, PepsiCo also offers its products in more than 200 countries. Its 22 global brands are its biggest sellers and represent its flagship food and beverage products. These 22 brands generate $1 billion in global sales every year. Just a few of these include Pepsi, Quaker, Gatorade, and Lipton. And, PepsiCo's international segments are growing much stronger than its North American divisions.

For example, Pepsi's revenue declined in its PepsiCo Americas beverage segment by 1.5% in the most recent quarter. Its performance in Europe wasn't much better, with revenue increasing by just 3%. By comparison, Pepsi grew revenue in its Asia, Middle East, and Africa segment by 6% in the same period.

Emerging market turmoil weighing on stocks
Not surprisingly, the turmoil in the emerging markets wreaked havoc on consumer-staples stocks over the past few weeks. Investors seem afraid that recent actions taken by the Federal Reserve will result in a stronger U.S. dollar. The Fed recently tapered its massive stimulus program again. This time, the U.S. central bank decided to trim another $10 billion in monthly bond purchases, from $75 billion to $65 billion.

This will hurt companies such as P&G, Coca-Cola, and PepsiCo, which derive a significant portion of their revenues from overseas. A stronger U.S. dollar will mean lower profits for these companies when their foreign-denominated sales are converted into U.S. dollars.

Keep emerging markets in mind going forward
It's worth noting that the actions taken by the Federal Reserve, to cut its monthly bond purchases, are due to improving economic conditions in the United States. Higher interest rates -- and by extension a stronger U.S. dollar -- are often symptomatic of a return to a healthy economy.

Nevertheless, the past few weeks have undoubtedly rattled investor nerves. The health of the emerging markets is now in doubt for multinationals such as P&G, Coca-Cola, and PepsiCo. Since their international segments account for such a large percentage of their sales, investors are starting to worry that their overseas divisions will become less profitable.

That's why investors might want to consider the state of the emerging markets before jumping into P&G, Coca-Cola, and PepsiCo.