Ed Al-Hussainy, portfolio manager at Columbia Threadneedle Investments, said the U.S. dollar has been mostly stable against developed-market currencies but has underperformed against emerging-market currencies, according to Bloomberg.

He cited carry-trade activity supported by higher real yields in Brazil, Mexico, Colombia and South Africa as a key driver. He also noted that the dollar's weakness persists despite low unemployment and steady U.S. growth, partly because the Federal Reserve has adjusted rates more slowly than many other central banks.