“Trust but verify,” a Russian proverb famously used by President Ronald Reagan during nuclear disarmament negotiations with the former Soviet Union, feels like an apt description of global investor sentiment toward U.S. markets. Stocks are poised to test new all-time highs again this week amid a parade of corporate earnings updates likely to consolidate forecasts of double-digit profit growth again this year, and a Federal Reserve interest rate decision that is likely to clear the way for further borrowing cost reductions over the next 12 months.