Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you expect consumer services companies to thrive over time, especially as the global economies recover and people feel more able to spend, the iShares Dow Jones US Consumer Services ETF (NYSE: IYC) could save you a lot of trouble. Instead of trying to figure out which companies will perform best, you can use this ETF to invest in a lot of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual fund cousins. The iShares ETF's expense ratio -- its annual fee -- is a relatively low 0.47%. The fund is fairly small, too, so if you're thinking of buying, beware of occasionally large spreads between its bid and ask prices. Consider using a limit order if you want to buy in.

This ETF has performed well, outperforming the world market over the past three, five, and 10 years. As with most investments, of course, we can't expect outstanding performances in every quarter or year. Investors with conviction need to wait for their holdings to deliver.

With a low turnover rate of 5%, this fund isn't frantically and frequently rejiggering its holdings, as many funds do.

What's in it?
Several consumer-services companies had strong performances over the past year. For example, priceline.com (Nasdaq: PCLN) surged 27%, enjoying faster growth, higher profit margins, and less competition in foreign markets. Growth in hotel bookings has also been strong, and even at home, Priceline has been performing well.

CVS (NYSE: CVS) popped 25%, posting impressive 20% revenue growth for its last quarter and 32% growth in its pharmacy services unit. CVS has outperformed its peers, such as beleaguered Walgreen (NYSE: WAG), which has seen its stock fall about 15% over the past year. A key problem for Walgreen has been the severance of its relationship with pharmacy benefits manager Express Scripts, which cost it gobs of customers and billions of dollars. The two companies have finally reconciled, though, which bodes well for them both. With Express Scripts acquiring Medco Health, another massive pharmacy benefits manager, it's more important than ever for both Walgreen and CVS to have strong deals with it.

McDonald's (NYSE: MCD), meanwhile, up 11%, continues to defy those who suggest that huge companies can't grow at a strong pace. Its revenue has been growing at an accelerating pace, recently in the double digits. Much of the company's recent success stems from its great geographical diversification, as it benefits from faster growth rates in emerging markets. Even at home, though, it has reaped rewards from innovations such as its line of coffees and new breakfast fare. Bears worry about rising commodity prices, as well as costs for labor and real estate.

The big picture
Demand for consumer services isn't going away anytime soon. A well-chosen ETF can grant you instant diversification across any industry or group of companies -- and make investing in and profiting from it that much easier.

If you like McDonald's, and would like to find other similarly dominant companies, check out our special free report: "3 American Companies Set to Dominate the World." (McDonald's is one of them.)