U.S. stock-market indexes closed at record levels on Wednesday with the Dow industrials ending above 23,000 for the first time. Analysts said stocks were supported by better-than-expected earnings results. The S&P 500 gained 1.90 points, or 0.1%, to 2,561.26, notching its 47th record close. The Dow Jones Industrial Average gained 160.16 points, or 0.7%, to 23,157.60, driven by a surge in shares of International Business Machine Inc. , which rose nearly 9%. The blue-chip index closed at a record for the 51st time this year. The tech-heavy Nasdaq Composite index ended fractionally higher at 6,624.22, also scaling a record.