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NEW YORK (CBSMiami) – A huge milestone for the Dow Jones Tuesday.

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It briefly crossed 23,000 points for the first time before closing just below it.

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The blue-chip index reached the 22,000 mark only in August. The Dow has hit four milestones this year, hitting 20,000 in January in a sign of ongoing investor optimism about corporate earnings and broader U.S. economic growth.

The Dow gained 40 points, or 2.2 percent, to close at 22,997. The S&P 500 and Nasdaq Composite indexes were largely flat on the day.

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Stocks have hit a succession of all-time highs in recent months amid unusually low volatility and despite a market that some analysts view as overvalued. That run-up also has been fueled by expectations for tax cuts, which means stocks could decline if talks over fiscal stimulus in Congress hit an impasse. Goldman Sachs analysts forecast that the S&P 500, which is hovering at a record high of 2,556 points, would fall to 2,400 if tax reform fails.