S&P 500® Concentration Risk Tracker

The top 10 SPY holdings represent 35.59% of the index (top 5: 25.97%). The HHI is 185 vs a 5-year average of 142, indicating elevated concentration. ACRI score: 81/100 (CRITICAL).

The ACRI is a composite index measuring equity market concentration risk across 3 signals: top-heavy concentration via HHI (40%), analyst target dispersion (35%), and sector imbalance (25%). Current score: 81/100 (CRITICAL).

Wall Street banks target the S&P 500 between 6200 and 8000 for year-end 2026 (mean: 7288). Current level: SPY-implied SPX ≈ 7101 (SPX approx = SPY × 10, derived). The wide range (1800 points) reflects disagreement about earnings growth and rate path.

When a small number of stocks dominate index returns, the index becomes vulnerable to idiosyncratic risks in those names. A negative earnings surprise or regulatory action against a top-5 holding can disproportionately impact the entire index, even if the broader economy is healthy.

The Magnificent 7 (Apple, Microsoft, NVIDIA, Amazon, Alphabet, Meta, Tesla) collectively represent approximately 30.44% of the SPY ETF as of 2026-04-17T17:36:53-05:00. This means roughly 7 companies out of 503 account for nearly a third of the index. For comparison, the top 7 stocks in an equal-weight index would represent just 1.4%. Source: SSGA SPY ETF holdings (ssga.com).

HHI (Herfindahl-Hirschman Index) = Σ(wᵢ²) × 10,000, where wᵢ is the weight of each holding as a decimal. Effective N = 1 / Σ(wᵢ²) = 10,000 / HHI. Current HHI: 185 (5-year average: 142). Effective N: 54 — meaning the index behaves like 54 equally-weighted stocks, despite having 503 holdings. A higher HHI and lower Effective N indicate greater concentration. These formulas are standard in industrial organization economics and are fully reproducible from public SPY holdings data.

SPY is the cap-weighted S&P 500 ETF; RSP is the equal-weight S&P 500 ETF. When SPY outperforms RSP, it means the largest stocks are driving index returns — a sign of narrow market breadth. When RSP outperforms, returns are more broadly distributed. Current YTD spread: SPY 0% vs RSP 0.2% (-0.2pp). Historically, extreme SPY-RSP divergence (cap-weight significantly outperforming equal-weight) has preceded periods of mean reversion where breadth recovers. Source: SSGA (SPY) and Invesco (RSP) public ETF data.

The SPY holdings data is sourced from SSGA's public daily disclosures (ssga.com). AhaSignals uses this data for analytical commentary under fair use. "S&P 500®" is a registered trademark of Standard & Poor's Financial Services LLC (S&P Global). AhaSignals is not affiliated with S&P Global. The SPY-implied SPX level shown (≈ 7101) is a derived approximation (SPX ≈ SPY × 10) and is not official S&P Global index data. Users wishing to redistribute this data should consult SSGA's and S&P Global's terms of use directly.

The ACRI is updated weekly or when significant market shifts occur — such as a major earnings release from a top-5 holding, a significant sector rotation, or a material change in Wall Street year-end targets. The SPY holdings component updates daily (SSGA publishes holdings each business day). The current snapshot is as of 2026-04-17T17:36:53-05:00.

When the top 10 holdings represent 35.59% of the index, a 10% drawdown in just those names would drag the entire index down approximately 3.6% — even if the remaining 493 stocks are flat. This amplification effect is the core mechanism of concentration risk. It works in both directions: concentrated indices can also rally faster when top holdings outperform. The ACRI measures how elevated this amplification risk is relative to historical norms.

As of 2026-04-17T17:36:53-05:00, the key S&P 500 concentration metrics (via SPY ETF holdings) are: Top 10 weight 35.59%, Top 5 weight 25.97%, Magnificent 7 weight 30.44%, HHI 185 (5-year average: 142), Effective N 54 (out of 503 holdings). The ACRI composite score is 81/100 (CRITICAL). All data sourced from SSGA SPY ETF daily holdings (ssga.com). Methodology version: v0.1-beta.

Different sources report different top-10 weights because of: (1) Data source — AhaSignals uses SPY ETF holdings from SSGA, while others may use S&P Global's official index constituents or other ETFs; (2) Timestamp — holdings change daily, so a Feb 10 snapshot differs from Feb 24; (3) Share class treatment — Alphabet has two share classes (GOOG + GOOGL) which some sources combine and others separate, affecting the top-10 cutoff; (4) Index vs ETF — SPY tracks the S&P 500 but has minor tracking differences due to cash drag and sampling. Our data is as of 2026-04-17T17:36:53-05:00 from SSGA (ssga.com). We show Top 10 = 35.59%.

Wall Street banks' year-end 2026 S&P 500 targets range from 6,200 to 8,000 — a spread of 1,800 points (8 banks). The mean target is 7,288 vs current SPY-implied SPX ≈ 7101. This wide dispersion reflects genuine institutional disagreement about AI capex returns, earnings growth trajectory, and Fed rate path. The ACRI uses this target dispersion as one of its three scoring components (35% weight). Sources: public research notes and press releases from each institution.