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For the first time since 2009, investors are pumping more money into U.S. stock funds than international stock funds. But investors seeking safety or stronger returns in homegrown funds may still be getting more foreign exposure than they bargained for.

Domestic funds have been adding more foreign flavor to their holdings in the last decade today, the average exposure, while still small, is more than three times what it was a decade ago. At the extreme end, one out of every 16 funds in Morningstar's U.S. equity category now has more than 25% of its assets in foreign companies, and some funds have more than 40% of their portfolios in foreign stock.

The increase comes at a time when many individual investors explicitly want the opposite: More domestic exposure, less foreign. Investors poured $1.4 billion into domestic stocks funds in the week ending Feb. 2, according to the latest estimates from the Investment Company Institute. That's the fourth straight week of net inflows for U.S. equity funds and a big reversal from 2010, when investors yanked an average of $7.3 billion out of U.S. stock funds each month. It's also the first time in 21 months that Americans are favoring domestic stock funds: International stock funds took in just $346 million in the week ending Feb. 2, the fourth straight week they pulled in less cash than U.S. stock funds.

And there may well be good reason for the shift. The U.S. could see GDP growth of up to 4.5% this year, much stronger than the expected 2% growth of developed foreign markets like Europe and Japan, says Frank Germack, the director of the capital management group at Rehmann Financial. And while emerging market economies should continue to grow at a faster clip in the long term, they have notched substantial gains and are likely due for pullback, says Rodney Johnson, the president of HS Dent.

But figuring out which funds offer purely domestic exposure isn't easy, especially because funds can change their mix over time. One clue: Most of the 171 domestic funds with large international holdings are sector funds. However, seven are domestic large-cap blend funds, including the Aberdeen Optimal Allocations Growth Fund, the Alpine Dynamic Dividend Fund, and the Oppenheimer Equity Investor Fund .

These seven blend funds tend to take what they call a tactical approach, meaning management can move quickly in and out of asset categories it feels present the best opportunities, says Shannon Zimmerman, associate director of fund analysis at Morningstar. So exposure to international stocks and all the asset classes the fund holds varies widely from year to year: For example, in 2007 the Aberdeen fund had 24% of its portfolio in international equities, and by the close of 2010, that allocation had risen to 43%. Fund managers that are looking to capture growth abroad won't try to hide that fact, but "investors really need to investigate and look at management notes" to make sure they know what they're buying, says Lee Munson, the chief investment officer at Portfolio Asset Management.

And even U.S. equity funds that invest primarily in American companies are likely exposed to international economies. Companies in the S&P 500 derive nearly half of their revenue from abroad, and a third of that international revenue comes from emerging markets, Zimmerman says. "Given how many companies are multinational, when you think about what their actual exposure is, is it where their headquarters is, or is it where they make their money?" Zimmerman says.

Figuring out a mutual fund's revenue mix is labor-intensive, but curious investors can find this information by looking at filings from the companies in a fund's portfolio, he says. Investors can also find those filings on Morningstar's website. While the right amount of international exposure varies among investors, many advisors suggest somewhere between 20 and 40% of an equity portfolio, depending on age, risk tolerance, and other factors.