The month of September 2026 was marked by the return of major central banks to monetary tightening: the ECB, the Fed, and the BoJ all raised their key interest rates by 25 bps, marking the first time this has happened in the same month. This move came in a context of high energy prices. Indeed, the conflict between Iran and the United States intensified again at the beginning of the month. Brent crude oil thus crossed the $100 mark again on September 9, for the first time since July.
The inflation indices published in September, covering the month of August, confirmed the divergence between the two sides of the Atlantic. In the eurozone, headline inflation accelerated sharply to 3.2%, while in the United States, headline inflation (CPI) remained stable at 3.4% year-on-year. Activity indicators once again demonstrated the resilience of developed economies in the face of high energy prices. In the United States, the August employment report was a significant upside surprise, and Q2 GDP growth was also strongly revised upwards, to 2.2% annualized from 1.5% previously. Similarly, the strength of the September PMI surveys (58.4 for the United States) made an impression and was interpreted as a sign that US growth was stronger than expected. In the eurozone, the composite PMI rose for the fourth consecutive month, reaching 53.1 in September, its highest level since April 2023. Meanwhile, China continues to stand out, as retail sales grew by only 0.4% year-on-year in August and investment continued to contract.
The ECB raised its key interest rates by 25 bps on September 10, increasing the deposit rate for the second time in three months, bringing it to 2.50%. The Fed unanimously raised the fed funds target range by 25 bps, to 3.75/4%, its first rate hike since 2023. Kevin Warsh presented this decision as the "removal of a dose of accommodation" rather than a tightening, while once again emphasizing that he did not intend to give any guidance on what comes next. As a result, bond yields rose sharply over the month, driven by the combined effect of higher oil prices and monetary tightening. The US 10-year yield rose by about 50 bps over the month, ending around 5.28%, its highest level since 2007, while the German 10-year yield rose by about 25 bps to 3.55%, after reaching its highest level since 2009. In Japan, the 10-year yield crossed the 3% mark for the first time since 1996, ending the month at 3.02%.
Equity markets paused in September, penalized by the rise in long-term rates. The S&P 500 ended the month roughly unchanged (about -0.8%). The Eurostoxx 600 fell by 2.5%, its first monthly decline in six months, the Nikkei rose by 0.7%, and finally, the MSCI Emerging edged down slightly (-0.8%), penalized notably by the Korean and Chinese markets. At the sector level, Energy (+2.8%) and Technology (+2.0%) were the only sectors to end the month in positive territory. Energy benefited from rising oil prices and ongoing disruptions at Hormuz and Bab el-Mandeb. Technology was supported by structural demand for semiconductors and AI infrastructure, with the exceptional performance of the M7 (+7.3%) standing out. Conversely, Automobiles (-8.1%) lagged behind, penalized by the deteriorating outlook for Volkswagen and Porsche, against a backdrop of ever-intensifying Chinese competition in Europe. The Financial sector (-7.3%), its worst monthly performance since March 2023, suffered from rising yields and, for online brokers, concerns related to the rise of AI agents. Real Estate (-7.2%) was hit by higher borrowing costs, while Commodities (-6.7%) were penalized by the correction in precious metals.
AI, particularly through Semiconductors, was the dominant theme of the month. Dario Amodei called for a slowdown in AI development in mid-September, citing concerns about humanity's safety. This triggered a brief but sharp sell-off in AI-related stocks around September 13 and 14. Rapid rebound: arguments from game theory, notably the idea that China's proximity to US frontier models makes a coordinated slowdown unlikely. On September 21, Meta launched Muse, its personal AI agent. The app immediately shot to first place, recording over 900k downloads in the first few days. META stock jumped 11% in the session. The AI sector saw a sharp rebound, partly on Inference: AMD +10%, Intel +12%, Arm +17%. At the same time, Cybersecurity delivered a remarkable performance in the background. When Dario Amodei called for a slowdown in AI development, AI infrastructure suffered a sharp drop, while cybersecurity moved in the opposite direction. The theme jumped 11% on September 14 alone. The theme was also supported by Palo Alto Networks, which guided for +23% revenue growth for 2027, explicitly citing AI as the main acceleration factor. Finally, after Hugging Face, Boston Scientific, Astrana Health, and Craneware, these cyberattacks validate the threat.
In August, CPR Megatrends rose by 1.49% compared to 1.05% for its benchmark index, the MSCI World (EUR). Among the best contributors, in addition to our overweight positions on the M7, were CPR AI (+7.8%), our Cybersecurity basket (+7.3%), and our Memory & HBM basket (+10.35%). Finally, with a more modest but still above MSCI World performance, our Data Center Construction basket was up 3.0%. Still within this theme, we added an Optical Networks basket at the end of the month. Among the detractors to performance were our positions in US banks with the Ishares US Banks ETF (-3.6%) and eurozone banks with Eurostoxx Bank futures (-1.9%). We moved from a neutral weighting in the financial sector to -2% at the end of the month.