A weak dollar sounds like a bad thing for the common American. Imports get more expensive as each buck buys fewer rands, or yuan, or rubles, and the cost of living increases as a result. But don't panic -- you can make up the difference, and much more, in your investment portfolio.

So how can you take advantage of currency trends that work to most American companies' disadvantage? You actually have a few options, short of trading currency directly. That can be a dangerous game, because your only route to profit is through correct exchange-rate guesses. You'd probably sleep better at night with an investment in U.S. companies that have a truly global reach.

If the entire continent of North America evaporated today, Coca-Cola (NYSE:KO) would lose just 29% of its revenues and 26% of its operating profits. When the value of a dollar drops, Coke makes more money since the majority of its sales are not in the United States. IBM (NYSE:IBM) generates just 39% of its sales in the U.S. and Canada. There are a few more names on that list, but from an investing perspective, that's nothing compared with buying into foreign companies instead.

There are 1,162 American Depositary Receipt (ADR) listings on the major American stock exchanges today, and it should be easy to find a tasty combination of business-performance and exchange-rate trends among them.

Take Volvo (NASDAQ:VOLV), for example. Shares of the Swedish truck maker gained 25.4% on the Stockholm exchange this year, a performance on par with all-American gainers like JPMorgan Chase (NYSE:JPM) and Activision (NASDAQ:ATVI). Business is strong, and the company has an enviable balance sheet to get it through the next cyclical downturn.

But the Volvo ADRs trading on Nasdaq got 52.6% more expensive over the same time period. That's the kind of performance you got from oil producer Marathon (NYSE:MRO) and CAPS five-star semiconductor manufacturing equipment maker FormFactor (NASDAQ:FORM). And the difference between the Swedish stock and the American equivalent is nothing but currency conversion.

The exchange rate stood at 7.93 Swedish krona per U.S. dollar at the start of the year. After an inexorable downward march, it's at 6.86 per dollar today. That's a 13% change in one year. The British pound sterling has improved 12% against the dollar over the same period, the euro by 10%, and the Swiss franc 7%. Put those free currency gains on top of the market returns produced by one of the many excellent companies trading in these markets, and you have yourself a winner.

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Activision is a Motley Fool Stock Advisor selection, FormFactor is a Motley Fool Hidden Gems pick, Coca-Cola should look familiar to Motley Fool Inside Value subscribers, and JPMorgan Chase is an Income Investor recommendation. Grab a free 30-day trial to any of our newsletters, and start boosting your portfolio today.

Fool contributor Anders Bylund is a Volvo and Coke shareholder, but he holds no other position in any of the companies discussed here. You can check out Anders' holdings if you like, and Foolish disclosure is always strong.