Every time Venezuela introduces a new, weaker currency exchange rate, some of the world’s largest companies face the decision of whether or not to adopt it. If they eventually do switch to the less favorable rate, it can result in multimillion-dollar charges that drag down balance sheets and earnings statements. At least 46 S&P 500 companies, about 10 percent of the total index, have told investors about potential exposure to Venezuela’s currency in the past year, according to a search of company filings compiled by Bloomberg. Venezuela currently has three legal exchange rates that are pre-set by the government, and companies that operate there have to decide which one they should use to value net monetary assets and report sales. The rates are currently at 6.3, 12 and 196.95 bolivars per dollar. The first two rates (called the Cencoex rate and the Sicad rate) are allowed for transacting government-authorized priority goods including food, medicine and car parts. […]