- S&P 500, SeptemberGlossary: An index of 500 large US companies, weighted by how much each is worth. When someone says “the market” without naming anything, this is usually what they mean.−0.5%YTD +11.8%
1.9% below its August 13 record; its September low came on the day the Fed hiked.
- 10-year TreasuryGlossary: The yearly return on a ten-year US government bond bought today and held to the end. It is the reference rate behind mortgages and most long-term borrowing.5.29%+54 bp
Its highest close since May 2002 and its biggest monthly rise since September 2022.
- S&P 500 stocks above their 200-dayGlossary: How many members of an index are taking part in a move, rather than a handful of large ones. We measure it as the share of S&P 500 companies trading above their own 200-day average price.40.3%−25.9 pts
The lowest since May 2025, and below March's low, while the index stayed 6% above its own.
- Chip index (SOX), SeptemberGlossary: An index of about 30 companies that design chips, make them, or build the equipment that makes them. It is the cleanest public proxy for the chip cycle.+9.5%YTD +78.3%
Technology was the only sectorGlossary: One of the 11 groups the stock market is split into by line of business, like technology, healthcare or energy. Every company in the S&P 500 belongs to exactly one. fund to rise, yet chips ended 13.7% below their June 22 record.
What regime we’re in
Trend: the index held, the average stock did not. The S&P 500 slipped 0.45% in September to 7,652, 1.9% below its August 13 record, still 6.0% above its 200-day averageGlossary: The average closing price over a set number of recent days, recalculated every day. It smooths out day-to-day noise to show the underlying trend. and up 11.8% for the year. Underneath, it split. The chip index rose 9.5% and the Nasdaq 100Glossary: An index of the 100 largest non-financial companies listed on the Nasdaq exchange. It leans hard toward technology, so it moves further than the S&P 500 in both directions. 3.2%, while the equal-weight S&P 500Glossary: A fund holding the same 500 companies as the S&P 500, but giving each one the same weight, so the largest handful cannot set the result on their own. (RSP) fell 4.8%, the Russell 2000Glossary: An index of about 2,000 smaller US companies. Smaller firms borrow at floating rates more often, so this index reacts quickly when interest rates move. 5.4% and developed international stocks (EFA) 3.3%. The share of S&P 500 members trading above their own 200-day average fell from 66.3% to 40.3%, its lowest since May 2025 and below March's low of 42.4%, when the index itself had broken below its 200-day. On September 21 the index closed within 0.4% of its record with only half of its members above their 200-day average; at the August 13 record the share was nearly 73%. The chart below shows the split and the breadthGlossary: How many members of an index are taking part in a move, rather than a handful of large ones. We measure it as the share of S&P 500 companies trading above their own 200-day average price. line.
VolatilityGlossary: How far and how fast a price swings over a period, whether up or down.: calm in stocks, not in bonds. The VIXGlossary: An index built from S&P 500 option prices that estimates how far the index is expected to swing over the next 30 days. Higher means traders are paying up for protection. rose 1.4 points to 16.3 and never closed above 17.8, so by the threshold the market has used all year (under 20 complacent, above 25 stressed) equity options stayed calm. Single-stock volatility rose too, but only back toward its 2026 norm: Cboe's constituent volatility index (VIXEQGlossary: The Cboe S&P 500 Constituent Volatility Index: the average expected 30-day swing of the individual stocks in the S&P 500, read from their options prices.) went from 35.8 to 39.8, below every month-end from February to July, and its ratio to the VIX held at 2.4, as in August. By last month's test, single-stock stress was not spreading. The bond market's version of the VIX, the MOVE indexGlossary: The bond market’s version of the VIX: an estimate of how far US Treasury yields are expected to move, built from options on Treasuries., jumped 35 points to 110.5, its biggest monthly rise since October 2024 and its highest close since March 27, above the 100 line that separates elevated from stressed.
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