Emerging market currencies such as the Argentine peso, the Turkish lira and the South African rand are suffering historic losses, and the rout is likely to continue, says Luis Costa, emerging markets strategist at Citigroup.

The lira dropped to a record low against the dollar, and the rand slid to a five-year nadir Monday. On Thursday, Argentina devalued the peso, letting it fall the most in 12 years.

"There's pressure on almost every high-yield currency now," Costa tells CNBC. And he sees more to come. "This isn't a one-week thing we're talking about."

Editor’s Note: 38 Trades That Could Turn $1,000 Into $49,000

The currency moves are "long overdue," given recent changes in international capital flows, Costa notes. Investors have been pulling money out of emerging markets amid anticipation of and then following the announcement of tapering by the Federal Reserve of its quantitative easing.

The capital flows are "especially felt in high-yielding economies," he argues. "They're high-yielding for a reason. They need to attract a lot of capital from abroad, and they're not."

Momentum is working against emerging markets now. "We are probably going to see overshooting before we reach more stable levels," Costa predicts.

"What now looks cheap will probably become cheaper in the near future."

Others see continued trouble ahead too. "The current environment is potentially very toxic for emerging markets," Eamon Aghdasi, a strategist at Societe Generale, tells Bloomberg.

"You have two very troubling things: uncertainty about the Fed policy, combined with concerns about growth, particularly in China. It's difficult to justify that it's time to go out and buy emerging markets at the moment."

Editor’s Note: 38 Trades That Could Turn $1,000 Into $49,000

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