Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you'd like to invest in consumer-staples companies because they focus on ... well, the staples that most people can't do without, no matter what the economy is doing, then the Consumer Staples Select Sector SPDR ETF (NYSE: XLP) 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 lots of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual fund cousins. The consumer staples ETF's expense ratio -- its annual fee -- is an ultra-low 0.18%.

This ETF has performed reasonably well, outperforming the S&P 500, on average, over the past 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 an extremely low turnover rate of 4%, this fund isn't frantically and frequently rejiggering its holdings, as many funds do.

What's in it?
Several consumer-staples companies had strong performances over the past year. Tobacco giant Altria (NYSE: MO), for example, rose 27%. Bulls love it for its dividend history -- and the fact that its customers crave its offerings. But some worry that its future may not be as profitable as its past, with increased regulations and taxes and drops in volume and market share. Thus, some prefer Altria's international counterpart, Philip Morris International (NYSE: PM), up 40%. It's poised to benefit from growing middle classes in developing nations worldwide, and faces fewer regulatory pressures. The company is a solid dividend payer, as well, but also carries a lot of debt. It has recently been rewarding shareholders with stock buybacks.

Sysco (NYSE: SYY), up 7%, isn't involved in selling staples to consumers, but in delivering them. It's a food distribution giant that has been challenged by our sluggish economy in recent years as well as by rising fuel costs. But we do seem to finally be pulling out of our economic malaise, slowly, and that means that folks will be eating out more often, which will be good for Sysco's business. Rising food prices can put pressure on profits, but shareholders can still rely on its solid dividend.

Other companies didn't do as well last year but could see their fortunes change in the coming years. Walgreen (NYSE: WAG), down 18%, was punished when it broke off its partnership with Express Scripts, losing many customers. The company seemed to be firing on all cylinders not so long ago, but right now, many investors are having trouble finding reasons to be optimistic.

The big picture
Demand for staples, by definition, 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.

Learn about the 5 ETFs That Could Soar in 2012. And if you're looking for some great investments beyond ETFs, consider these 12 Dividend Stocks for 2012.

Longtime Fool contributor Selena Maranjian, whom you can follow on Twitter @SelenaMaranjian, holds no position in any company mentioned. Click here to see her holdings and a short bio. The Motley Fool owns shares of Altria Group and Philip Morris International. Motley Fool newsletter services have recommended buying shares of Sysco and Philip Morris International. 

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