The first exchange-traded funds (ETFs) were based on broad-market indexes, such as the S&P 500. Simple enough, right? Buy shares of S&P 500 SPDRs (AMEX:SPY), and you're instantly invested in the companies of the S&P 500, which make up some 80% of the overall market.

Times have changed, though. As ETFs explode in popularity, we're seeing more and more ETFs launched, and they're getting less focused on big indexes and more on various market niches. Witness one such development: emerging-market ETFs -- and mutual funds, for that matter.

In a recent MarketWatch article, Barbara Kollmeyer discussed this new trend, profiling some new emerging-markets ETFs and mutual funds. She quoted Mark Mobius of the new Templeton Emerging Markets Small Cap Fund, who said, "One of the things we were getting from our customers was 'Why aren't you in Estonia? Why aren't you in Romania or Vietnam?'" This is one reason given for the launch of some new offerings -- many of which focus on the smaller companies you'll find in these countries.

The comment made me think of the only emerging-market investment currently in my portfolio -- the Vanguard Emerging Markets Stock Index Fund (FUND:VEIEX). (Its ETF counterpart is the Vanguard Emerging Markets Stock ETF (AMEX:VWO)). While the name of the fund might make you assume it invests all over the emerging-market world, it's actually heavily concentrated in just a few nations. According to Morningstar, nearly 70% of it is invested in South Korea, Taiwan, Hong Kong, South Africa, and Brazil -- with about 60% in Asia (excluding Japan). The Templeton Emerging Markets ETF (NYSE:EMF), similarly, has about 56% of its assets in non-Japan Asia, with 61% in South Korea, Hong Kong, Taiwan, Brazil, and Turkey. The popular iShares MSCI Emerging Markets Index Fund (NYSE:EEM) isn't vastly different.

So if you want broader exposure, you need to keep looking. One place to check out might be Mobius' new fund, which is expected to invest in the likes of Nigeria, Bolivia, Peru, Panama, and Vietnam.

If you want to focus on specific countries, you'll find you can often do so. The iShares MSCI Malaysia Index Fund (NYSE:EWM), for example, will plunk you into Malaysian banks, as well as utilities, food companies, and more. The iShares S&P Latin America 40 Index Fund (NYSE:ILF) will put you in Brazil, Mexico, Chile, and Argentina, with the first two making up more than 80% of the fund). There are lots of other funds and ETFs focused on less high-profile nations and regions.

Should you even do it?
One question to ponder before jumping into any international investment, emerging-market or not, is how much you really know about the regions involved. Not all countries or regions are as stable as ours. It can be risky, if you don't know what you're doing. I recommend taking a little time to learn more about international investing. The following articles will shed some light:

Another option worth exploring is our brand-new Motley Fool Global Gains international investing service, headed by Motley Fool Senior Analyst Bill Mann. Try it free for 30 days and see for yourself.

You can learn much more about ETFs by checking out our ETF Center, which features info on how ETFs stack up against mutual funds, how to develop an investment strategy with ETFs, and how to avoid pitfalls and ETF impostors.

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Longtime Fool contributor Selena Maranjian owns shares of the Vanguard Emerging Markets Stock Index Fund and recently had a Motley Fool CAPS ranking of 1,472 out of 12,412. Want your own rating? Try out our new Foolish stock-rating community for yourself.