My view:
September shows that the market is becoming more selective, not simply bullish or bearish.
Tech and AI remained strong, but this support is concentrated in fewer stocks.
Around 78% of S&P 500 stocks fell, showing weaker market breadth.
High Treasury yields are becoming a bigger challenge because they increase financing costs and pressure valuations.
Higher oil prices could make inflation harder to control.
AI spending remains strong, but October earnings will test whether the growth can justify high valuations.
Bottom line:
I would watch earnings + Treasury yields more closely than the index itself. If earnings continue growing while yields stabilize, the market could remain supported. If yields and oil rise while earnings weaken, volatility could increase.