How concentrated is this portfolio, really?
Position and sector weights, top-three share, Herfindahl index and effective number of holdings for a dated example portfolio, with what each number means for the next decision.
Example as of 2026-10-07 (closing prices) · version 1 · eight real companies, illustrative share counts.
Position weights
| Holding | Sector | Shares | Close | Value | Weight |
|---|---|---|---|---|---|
| AAPL Apple Inc. | Information technology | 60 | $336.67 | $20,200 | 19.2% |
| NVDA NVIDIA CORP | Information technology | 80 | $237.47 | $18,998 | 18.0% |
| MSFT MICROSOFT CORP | Information technology | 30 | $529.76 | $15,893 | 15.1% |
| JPM JPMORGAN CHASE & CO | Financials | 40 | $329.58 | $13,183 | 12.5% |
| DAL DELTA AIR LINES, INC. | Industrials (airline) | 150 | $82.97 | $12,446 | 11.8% |
| XOM Exxon Mobil Corp | Energy | 70 | $164.05 | $11,484 | 10.9% |
| PG PROCTER & GAMBLE Co | Consumer staples | 50 | $147.82 | $7,391 | 7.0% |
| HD HOME DEPOT, INC. | Consumer discretionary | 20 | $285.77 | $5,715 | 5.4% |
Concentration measures
| Measure | Value | What it means |
|---|---|---|
| Largest position | 19.2% | AAPL alone moves the book 1.92% for every 10% it moves. |
| Top three | 52.3% | AAPL, NVDA, MSFT drive most of the outcome. |
| Herfindahl index | 0.142 | Sum of squared weights; 0.125 would be eight equal positions. |
| Effective holdings | 7.1 | The book behaves like 7.1 equal-weight positions, not 8. |
| Largest sector | 52.3% | Information technology. |
Against a 10% position cap, AAPL (19.2%, 9.2 pp over), NVDA (18.0%, 8.0 pp over), MSFT (15.1%, 5.1 pp over), JPM (12.5%, 2.5 pp over), DAL (11.8%, 1.8 pp over), XOM (10.9%, 0.9 pp over) breach the limit. Trimming is one response; the decision depends on whether the evidence for each position still holds.
Assumptions
- Share counts are illustrative; prices are the 2026-10-07 close; weights use market value.
- Company figures are the latest annual 10-K values in SEC XBRL; "Not reported" means the company does not tag that figure.
- Scenario returns and oil channel classifications are stated assumptions, not estimates.
Sources
- FRED DGS10: 10-year Treasury yield · as of 2026-10-07
- FRED DCOILWTICO: WTI crude · as of 2026-10-06
- SEC 10-K AAPL 0000320193-25-000079 · FY ending 2025-09-27
- SEC 10-K MSFT 0001193125-26-323660 · FY ending 2026-06-30
- SEC 10-K NVDA 0001045810-26-000021 · FY ending 2026-01-25
- SEC 10-K JPM 0001628280-26-008131 · FY ending 2025-12-31
- SEC 10-K XOM 0000034088-26-000045 · FY ending 2025-12-31
- SEC 10-K PG 0000080424-26-000103 · FY ending 2026-06-30
- SEC 10-K HD 0001628280-26-019436 · FY ending 2026-02-01
- SEC 10-K DAL 0000027904-26-000013 · FY ending 2025-12-31
- Daily closes: Polygon.io grouped daily bars, 2026-10-07
Apply this to your holdings
One holding per line as ticker, shares, price (for example AAPL,25,336.67). Your holdings stay in this browser, carry through checkout and reopen in Capital Command. Market Ontology Desk.