The Dow Jones is up today primarily because of investors' optimism following August inflation data that largely matched expectations. This inflation data has reinforced hopes that the Federal Reserve will cut interest rates in its upcoming September meeting, encouraging buying in the stock market. On Thursday, the Dow rose 617 points, or 1.36%, closing above the 46,000 mark for the first time, signaling strong market confidence despite economic uncertainties. Market participants view the inflation data as supportive of a Fed rate cut, which is generally positive for stocks as it reduces borrowing costs and stimulates economic activity. Additionally, fears related to tariffs and economic weakness have been somewhat alleviated by these developments, further boosting market sentiment today. In summary, the Dow is up today because investors are anticipating a Federal Reserve interest rate cut based on the inflation data released, which has aligned well with market expectations and fueled a broader stock rally.