Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. European companies, beaten down by their nations' economic woes, could be bargain-priced right now. Want to add some to your portfolio? The Vanguard MSCI Europe ETF (NYSE: VGK) 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 Vanguard ETF's expense ratio -- its annual fee -- is a very low 0.14%. (Vanguard is known for low fees.) It also recently yielded a hefty 4.8%, thanks in part to the depressed prices of its component stocks.

This ETF has delivered returns close to those of the MCSI EAFE index, beating it slightly over the past three years and underperforming it over the past five. 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 very low turnover rate of 6%, this fund isn't frantically and frequently rejiggering its holdings (as many funds do).

What's in it?
Some European companies had strong performances over the past year. Based in Denmark, Novo Nordisk (NYSE: NVO) is the world's largest insulin maker and specializes in diabetes care and biotechnology. It gained some 18% over the past year. Its diabetes drug Victoza may be effective in fighting obesity, and if it ends up approved for such a use, that could be hugely lucrative for the company.

Many other companies didn't do as well last year, but could see their fortunes change. Telefonica (NYSE: TEF) plunged about 42%, for example. Yes, it's based in troubled Spain, but it gets nearly half its revenue from operations in Latin America, and some 60% of its profits from there. Better still, economies such as Brazil are growing much more rapidly than those in Europe, which bodes well for Telefonica's future. The stock also sports an attractive dividend yield.

Banco Santander (NYSE: SAN), meanwhile, lost 40%. Also based in Spain, at the end of last year, it had almost as many branches in Latin America as in Europe (more than 6,000 in each). The stock also has a huge yield, and though there are plenty of risks to consider, it does appear undervalued at recent levels. Furthermore, it's in a position to possibly buy assets of other, more troubled companies, while expanding into additional faster-growing markets like China.

Oil giant Total (NYSE: TOT), based in France, shed 15% over the last year, but has a sustainable and growing dividend that recently yielded nearly 6%. Revenue and earnings have been growing at accelerating rates. The stock took a hit from some gas leaks in recent months, and an attack on its Yemeni operations, but those are not necessarily long-term problems. With its P/E ratio near 6, the stock seems attractively priced, and the company is beefing up its operations globally.

The big picture
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.

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