Stock Market Midday, Sept. 30: Markets Rise on Softer Inflation Data, Investors Await Micron Earnings

U.S. markets rose midday on September 30, 2026, following softer-than-expected August PCE inflation data (3.4% year-over-year), which reduced expectations for an October rate hike. The Nasdaq Composite led gains at +0.99%, while the S&P 500 and Dow Jones showed more modest gains. However, analysts warn of concentration risk in AI stocks and deteriorating market breadth, with single-stock volatility rising despite major indexes near all-time highs.