This week's list of decliners on the Dow Jones Industrial Average (DJINDICES:^DJI) is lengthy. Twenty-six of the 30 Dow components lost ground, and the Dow lost 1.77% for the week. The broader S&P 500 (SNPINDEX:^GSPC) fell 1.48% on the week.

The biggest loser on the Dow this week was DuPont (NYSE:DD). The chemical maker fell 8.4% for the week after reporting a terrible third-quarter earnings report. Sales fell nearly 10%, and earnings were cut by more than one third. To fix matters, DuPont is cutting employees in hopes of maintaining profits. Sales were negatively affected 4% by currency headwinds.  

Do-everything manufacturer 3M (NYSE:MMM) fell 5.3% after reporting disappointing earnings as well. Sales fell 0.4% in the quarter to $7.5 billion, and management was forced to lower full-year guidance to earnings of $6.27 to $6.35 per share. A close look at the numbers reveals that organic local-currency sales grew 2.2%, so there was a big impact on both the top and bottom line just because of currency adjustments.  

Our third biggest loser in the Dow was General Electric (NYSE:GE), which dropped 4.2% on the week. The company reported earnings before the market opened on Friday, but investors had the weekend to look them over and came away less impressed. The company hit bottom-line estimates but missed on the top line. The excuse? You guessed it. Currency headwinds knocked down growth, which would have been $1.1 billion without this challenge.

If you're taking away a theme from this week it's that currency plays a big role in company earnings. The strong dollar now has the effect of lowering revenue and earnings produced in the rest of the world. DuPont, 3M, and GE all have global operations ,so they're taking a hit because of their exposure overseas.

Don't give up on overseas
Currency challenges have hit companies this quarter, but with QE3 hitting and the normal ebbs and flows of the currency market, these challenges will become tailwinds eventually. Plus, profiting from our increasingly global economy can be as easy as investing in your own backyard. Our free report "3 American Companies Set to Dominate the World" shows you how. Click here to get your free copy before it's gone.