Standard & Poor's, whose unprecedented downgrade of U.S. debt triggered a worldwide stocks sell-off, is pushing back against a U.S. government proposal that would require credit raters to disclose "significant errors" in how they calculate their ratings. S&P, which was accused by the Obama administration of making an error in its calculations leading to Friday's downgrade, raised concern about the proposed new corrections policy and other issues in an 84-page letter to the Securities and Exchange Commission, dated August 8. The SEC is weighing sweeping new rules designed to improve the quality of ratings after their poor performance in the...