Morgan Stanley calls them “The Fragile Five.” They’re a group of nations that are home to 1.8 billion people and roughly $6 trillion in annual economic activity. They also have some of the world’s most vulnerable currencies which, as a result, have been plunging against the dollar and hammering returns for U.S. investors.

Brazil, India, Indonesia, South Africa and Turkey have become pariahs among emerging market investors, tainting the image of many of their brethren, too. But these countries have only themselves to blame because they grew addicted to imports and paid for them with foreign funds.

Yet it pays to track the moves of these struggling economies. “Countries that announce structural reforms are bound to get more investor interest,” says Russ Koesterich, chief investment strategist for BlackRock Inc. Koesterich adds that emerging markets are now “undeniably cheap…it’s an unappreciated asset class.”

The iShares MSCI EM Index ETF is down roughly 10 percent over the past year versus a 23 percent gain for the S&P 500.

Alec Young, global equity strategist at S&P Capital IQ, believes low valuations aren’t enough. “Everything starts with the currency against the dollar,” he says, predicting that some of the weakest global currencies such as the Turkish lira and the South African rand may weaken further as current economic stresses deepen. “It’s a risky way to bottom-fish.”

Jeremy Schwartz, research director at WisdomTree, is also keeping a close on eye on the beleaguered emerging market currencies. “A weak currency can actually bolster returns for U.S. investors once they reverse course,” he says.

For now, these strategists say investors should focus on emerging markets that run trade surpluses or at least have proven their ability to keep attracting foreign funds, are implementing meaningful reforms, and are expected to deliver export-fueled growth.

iShares MSCI Mexico Capped ETF (EWW)

Mexico typically generates a $60 billion annual trading surplus with the U.S., according to census.gov.  And the trend should show no sign of letting up in 2014, as U.S. GDP is expected to rise nearly 3% this year, creating an even stronger appetite for Mexican imports. Even though the U.S. and Mexico are deeply inter-twined, investor interest has diverged as this ETF has underperformed the S&P 500 by roughly 30 percentage points both on a one-year and two-year basis (the latter isn’t annualized; it’s absolute).

Mexican governance is also getting higher marks as President Enrique Pena Nieto pursues his “Pact for Mexico,” which has greatly increased bipartisanship. The country has been quashing telecom monopolies while opening up its energy sector to foreign investment, and that step recently led S&P to boost its credit rating for Mexico, calling the energy reforms a “watershed moment.”

The iShares MSCI Mexico Capped ETF carries a 0.49 percent expense ratio and has generated a 15.6 percent annualized return over the past five years, according to Morningstar.

Market Vectors Vietnam ETF (VNM)

Though many emerging market economies have only begun to react to the various economic stresses of 2013, Vietnam has already taken its tough medicine. Several years ago, its economy was suffering from high inflation due to a poor national infrastructure.

Its banking sector also grew troubled, as unpaid loans piled up on bank balance sheets.  In response, the government created the Vietnam Asset Management Co. to snap up those bad loans, and a now-healthier banking sector has begun lending again. Inflation has also come under control thanks to tough monetary policies.

Equally important: nearly two decades of persistent trade deficits are finally coming to an end. Though Vietnam ran a $1 billion trade deficit in the first half of 2013, it has run a roughly $1.5 billion trade surplus in the five months ended November 2013 thanks to surging exports as multi-nationals start to close higher-cost factories in China and re-open them in Vietnam.

As a result, investors have begun to focus on Vietnam, and shares of this ETF are up more than 8 percent in 2014. Still, the tough stretch the Vietnamese economy suffered from 2010 through 2012 has hurt this fund’s longer-term performance––it trades roughly 5 percent below its August 2009 offering price. The fund’s 0.76 percent expense ratio is a bit stiff, but Vietnam’s strengthening economic outlook should help investors tolerate that high expense load.

The emerging markets rebound will play out at a different pace for various countries. Some of the more poorly-performing stock markets still aren’t safe to buy, as investors await signs of more tangible reforms and a reversal of persistent trade deficits.

But other emerging markets such as Mexico, Vietnam, and a handful of countries in Asia have a much brighter economic outlook. These markets haven’t kept pace with the surging U.S. stock market in recent years, and as result, often sport more attractive valuations.