Donald Trump’s surprise election win should bring some welcome relief to banks. A Republican Party in control of Congress also usually appeals to financial markets. The president-elect’s erratic positions on other important issues, however, could turn those short-term gains into long-term pain. U.S. bank stocks rallied early on Wednesday after learning that Trump is set to become the country’s 45th president. As with Britain’s vote in June to leave the European Union, gyrations in government debt and currency markets could mean brisk business for traders of bonds, currencies and commodities. A commitment to spending on American roads and bridges, reinforced