The drag on corporate profits from fluctuations in foreign-exchange rates is getting worse as the second quarter comes to a close.

Currency-market volatility that's almost doubled in the past 12 months poses the biggest threat to earnings of any year on record, according to FiREapps, a Scottsdale, Arizona-based company that advises businesses and makes software to help reduce the impact of currency swings. That would surpass the approximate US$47 billion in losses that North American companies reported in 2012.

Companies from Facebook Inc. to Microsoft Corp. have already warned that their bottom lines will take a bigger hit than in the first three months of the year. While the dollar's surge is the main culprit, swings in everything from the euro to emerging-market currencies are magnifying the pain and making it more expensive to hedge.