The U.S. Dow stock index finished above 40,000 for the first time on Friday as hope continued that the U.S. economy will remain stable and the country’s central bank could begin cutting the key interest rate in the fall. The 30-issue Dow Jones Industrial Average gained 134.21 points, or 0.34 percent, to close at 40,003.59. A day earlier, it briefly topped the 40,000 threshold for the first time to mark an intraday high of 40,051.05, but closed below the line. Buying gathered steam on Friday as recent government data, which signaled slowing inflation and normalization in the labor market, appar…