Investment case
iShares Russell 2000 ETF
IWM · 5 developments mapped · last assessed 2026-09-21
Market Ontology has mapped 5 macro, policy, and market developments to iShares Russell 2000 ETF since 2026-09-20. Each one is traced from the driver to the valuation assumption it moves, and the valuation below is run on the same engine the subscription uses.
Valuation
No validated run has been published for IWM yet, so no modelled value is shown. The IWM valuation is in the public catch-up queue.
Subscribers do not wait for the weekly cycle: they run IWM on demand, against live prices and the latest filings, and change any assumption the developments below move.
Filed financials
Current case
- Main threat
S&P 500 top 10 weight hits ~40%, highest concentration since mid-1960s
Indirect effect of capital allocation; disproportionate focus on mega-caps may divert capital from smaller companies, impacting liquidity and valuation multiples.
· Moves cost of capital for small caps, liquidity premium, terminal multiple for small caps
- Open question
S&P 500 Top 10 Weight Reaches 40%, Highest Level Since Mid-1960s
Potential for rotation out of mega-cap into broader market, or underperformance due to capital allocation.
· Moves market risk premium for small cap, terminal multiple (if capital shifts towards value/small cap)
What changed, by assumption
- 2026-09-21S&P 500 top 10 weight hits ~40%, highest concentration since mid-1960s
- 2026-09-21S&P 500 top 10 weighting hits 40% as AI mega-caps dominate index concentration
- 2026-09-20S&P 500 Top 10 Weighting Reaches 40% Concentration
- 2026-09-20S&P 500 top 10 weighting reaches 40%, matching mid-1960s records
- 2026-09-21S&P 500 Top 10 Weight Reaches 40%, Highest Level Since Mid-1960s
Event impact log
Full ledger →| Date | Mechanism | Direction | Horizon | Impact |
|---|---|---|---|---|
| 2026-09-21 | S&P 500 top 10 weight hits ~40%, highest concentration since mid-1960s | Bearish | 3-12m | 0.70 |
| 2026-09-21 | S&P 500 top 10 weighting hits 40% as AI mega-caps dominate index concentration | Bearish | 3-12m | 0.60 |
| 2026-09-21 | S&P 500 Top 10 Weight Reaches 40%, Highest Level Since Mid-1960s | mixed | 3-12m | 0.50 |
| 2026-09-20 | S&P 500 Top 10 Weighting Reaches 40% Concentration | Bearish | 1-3m | 0.60 |
| 2026-09-20 | S&P 500 top 10 weighting reaches 40%, matching mid-1960s records | Bearish | 1-3m | 0.60 |