The largest emerging markets, whose economies grew more than four-fold in the past decade, are making losers out of everyone from central bankers to Procter & Gamble Co. as their currencies post the biggest declines since at least 1998.

For the first time in 13 years, the real, ruble and rupee are weakening the most among developing-nation currencies, while the yuan has depreciated more than in any other period since its 1994 devaluation. P&G, the world's largest consumer-goods maker, cut its profit forecast for the second time in two months last week in part because of currency losses. Brazil's Fibria Celulose SA, the biggest pulp producer, asked banks to loosen restrictions on dollar loans as the real hit a three-year low.

Investors are fleeing the four biggest emerging markets, known as the BRICs, after Brazil's consumer default rate rose to the highest level since 2009, prices for Russian oil exports fell to an 18-month low, India's budget deficit widened and Chinese home prices slumped. Investors are bracing for more losses as economic growth slows.