Crude oil’s worst run in four months is hurting more than just commodity traders. Currencies from the Norwegian krone to Brazil’s real are tumbling as investors revise economic growth expectations for petroleum-exporting nations. Mexico’s peso slumped to its weakest since a 1993 revaluation, while the Canadian dollar fell to a six-year low. “It is oil today,” Greg Anderson, Bank of Montreal’s global head of foreign-exchange strategy, said by phone from New York. “The economies in these countries have slowed down enough that they’re cutting interest rates, so now it’s about that, in addition to commodity-price weakness.” The Norwegian krone led losses by commodity currencies, sliding 0.6 percent to 8.2236 per dollar as of 2:30 p.m. in New York. Brazil’s real declined 0.2 percent to 3.1955 per dollar, approaching its lowest since March. Oil fell below $50 a barrel in New York for the first time since April 6. It’s […]