Key takeaway
The S&P 500 (SPX) is trading at historically high valuation levels, but the technology sector has experienced the smallest increase in forward price-to-earnings (P/E) relative to its 10-year average of any sector. Elevated overall index valuations are driven primarily by expansions in nine non-technology sectors rather than a concentrated AI-driven tech bubble.
What the 10-year forward P/E comparison shows
- The forward P/E ratio is a common measure of market valuation that compares expected earnings to current prices. Comparing current forward P/E to its 10-year average normalizes valuation trends across sectors.
- When sectors are measured against their own 10-year forward P/E averages, technology registers the smallest relative increase. By contrast, most other sectors have expanded their forward P/E ratios materially versus their 10-year norms.
- The result: headline statements that the market is expensive are accurate, but attributing elevated valuations solely to an AI-fueled tech bubble is incomplete.
Why the AI bubble narrative is incomplete
- The AI narrative is powerful and visible: a subset of technology companies that emphasize artificial intelligence has driven investor attention and price momentum. However, a broad-sector valuation analysis shows that the aggregate tech sector has not experienced the largest P/E expansion on a relative basis.
- Market-level valuation pressure can come from several sources besides technology: consumer discretionary, health care, industrials, financials and other sectors can, and have, contributed to higher index-level forward P/Es.
- Focusing only on AI or a handful of headline names can create confirmation bias. A sector-level comparison against 10-year averages provides a more balanced view of where valuation expansion has occurred.
Practical implications for professional traders and institutional investors
- Portfolio attribution: Reassess attribution models to separate price performance from valuation multiple expansion. If non-tech sectors are leading multiple expansion, then rebalancing or hedging should reflect sector-level drivers, not just tech exposure.
- Risk management: A market labeled "expensive" requires precise identification of where that expense is concentrated. If technology shows the smallest relative P/E increase, blanket tech hedges may be less effective than targeted sector or factor hedges.
- Earnings sensitivity: Elevated forward P/Es outside technology mean the index may be more sensitive to earnings surprises in those expanded sectors. Stress-test portfolios for downside scenarios that affect sectors with the largest multiple expansions.
How to use this insight in valuation and modeling work
- Use relative forward P/E metrics by sector: Compare each sector’s current forward P/E to its historical (10-year) average rather than comparing all sectors to a single benchmark.
- Decompose index valuation change into two components: (1) weighted earnings growth and (2) weighted P/E change. This isolates whether index-level valuation moves stem from earnings momentum or multiple expansion across sectors.
- Monitor cross-sector rotation: If multiple expansion is concentrated outside tech, look for signals of rotation risk that could reverse those expansions—macro shocks, interest-rate moves, or earnings disappointments in sectors with the largest relative P/E increases.
Short-term and medium-term outlook considerations
- Short term: Elevated valuations in several non-tech sectors imply vulnerability to shifts in growth expectations, policy changes, or macro volatility. Price action in headline AI names may continue to dominate headlines, but broader sector valuation dynamics will determine index-level risk.
- Medium term: If earnings catch-up in sectors with expanded multiples occurs, valuations could normalize without large price disruption. Conversely, if earnings fall short in those sectors, index downside may be larger than implied by a tech-centric bubble narrative.
Actionable checklist for traders and analysts
- Recalculate sector forward P/Es against 10-year averages monthly.
- Attribute index moves to sector-level multiple changes versus earnings changes.
- Run scenario analyses that remove AI or top technology names from the index to quantify how much index valuation is dependent on tech performance.
- Implement targeted hedges for sectors showing the largest relative P/E increases rather than blanket technology hedges.
Conclusion
The headline that the U.S. stock market is historically expensive is accurate. The more important, and more nuanced, observation is that technology — despite high-profile AI momentum — has shown the smallest relative increase in forward P/E compared with its own 10-year average. Nine other sectors have contributed to the overall expansion in S&P 500 valuations. For professionals, this means reassessing attribution, refining risk management, and focusing valuation and scenario work at the sector level rather than defaulting to a tech-only bubble thesis.
(Tickers: SPX, AI)
