Exxon Mobil Corp lost its top-tier credit rating from Standard & Poor’s on Tuesday – the first time in almost 70 years, as an oil price rout makes it tougher for the largest producer of crude to fund projects and return big amounts of cash to shareholders. S&P, a unit of McGraw Hill Financial Inc, cut Exxon’s rating to “AA+” from “AAA,” a one-notch decrease that leaves drugmaker Johnson & Johnson and Microsoft Corp as the only U.S. companies with the coveted, sterling rating. S&P issued a stable outlook for the company’s rating, which is still as strong as S&P’s rating for the U.S. government. Exxon, in a statement about the downgrade, said it will focus on long-term shareholder value, regardless of oil price volatility. “Nothing has changed in terms […]