Key Takeaways
- The S&P 500 posted its biggest September percentage gain since 2010, rising 3.53% for the month and 7.79% for the quarter, while the Dow Industrials saw its best September since 2019, climbing 1.87% in September and 5.22% in Q3.
- Berkshire Hathaway (BRK.A, BRK.B) is reportedly in talks to acquire Occidental Petroleum's (OXY) petrochemical unit, OxyChem, for approximately $10 billion, marking Warren Buffett's largest deal since 2022.
- The Nasdaq led quarterly gains, surging 11.24% in Q3 and 5.61% in September, reflecting broad strength across technology and growth sectors.
- The municipal-bond market is set to deliver its best monthly performance in nearly two years, while the FTC has filed an antitrust lawsuit against Zillow (ZG, Z) and Redfin (RDFN) over online rental listings.
Market Performance Highlights
U.S. equity markets concluded September and the third quarter of 2025 with significant gains, with the S&P 500 and Dow Industrials recording their strongest September performances in over a decade. The S&P 500 closed up 28.47 points (0.43%) at 6,689.68, contributing to its 3.53% gain for September and a robust 7.79% rise for the quarter.
The Dow Jones Industrial Average advanced 84.25 points (0.18%) to 46,400.32, marking its best September percentage gain since 2019. For the month, the Dow climbed 1.87%, and it posted a 5.22% increase for the quarter.
The technology-heavy Nasdaq Composite also saw substantial growth, closing up 72.89 points (0.32%) at 22,664.04. The Nasdaq led the major indices in quarterly performance, surging 11.24% in Q3, and gained 5.61% in September.
Corporate Developments
Berkshire Hathaway (BRK.A, BRK.B) is reportedly in advanced discussions to acquire Occidental Petroleum's (OXY) petrochemical division, OxyChem, in a deal valued at approximately $10 billion. This potential acquisition would represent Warren Buffett's largest transaction since 2022, with OxyChem having generated nearly $5 billion in sales over the past year.
In other corporate news, the Federal Trade Commission (FTC) has filed a lawsuit against real estate technology companies Zillow (ZG, Z) and Redfin (RDFN), alleging antitrust violations related to their online rental listings. Meanwhile, former President Donald Trump is expected to announce a deal with Pfizer (PFE) aimed at lowering drug prices.
Economic and Political Landscape
The municipal-bond market is poised to achieve its strongest monthly performance in nearly two years, indicating renewed investor interest and stability in the sector. However, independent trading houses in the massive $9.6 trillion-per-day foreign exchange market are facing significant challenges in competing with more established banks, according to a new report.
On the political front, the Senate is scheduled to hold votes around 5:30 PM ET on procedural motions to overcome filibusters for both Democratic and Republican government funding bills. Democratic leader Chuck Schumer is reportedly threatening a government shutdown in opposition to Donald Trump's policies. Internationally, Germany's Lufthansa (LHA.DE) could face a pilot strike after its pilots' union, VC, voted in favor of a walkout due to an ongoing dispute over pensions.
Ed Liston is a senior contributing editor at TheStockMarketWatch.com. An active market watcher and investor, Ed guides an independent team of experienced analysts and writes for multiple stock trader publications.