How to Compare Institutional Portfolios Using Concentration Metrics
Not all 13F portfolios carry equal signal. Here is how Top-5 concentration and position count help distinguish conviction stock pickers from index trackers.
Not all institutional portfolios carry equal signal. Some filers hold thousands of positions spread thinly while others concentrate capital in high-conviction bets. Concentration metrics help you distinguish signal from noise on 13F Insight.
TL;DR
- Top-5 and Top-10 ratios reveal how much is in the largest positions.
- Above 30% top-5 = active stock-picking conviction.
- Below 15% top-5 = index-tracking or broad-mandate.
- Position count alone is misleading.
Key Metrics
| Metric | What It Reveals |
|---|---|
| Top-5 Weight | Capital in the biggest bets |
| Top-10 Weight | Breadth of conviction |
| Position Count | Portfolio breadth (can mislead) |
Real Examples (Q4 2025)
| Filer | AUM | Top-5 | Positions | Type |
|---|---|---|---|---|
| Berkshire Hathaway | $274B | ~70% | ~40 | Ultra-concentrated |
| Capital World | $735B | 19.8% | 574 | Active picker |
| Dimensional | $477B | 17.9% | ~15K | Factor-based |
| Vanguard | $6.9T | 24.8% | 17K | Index tracker |
| Norges Bank | $935B | 26.3% | 1,577 | Sovereign fund |
How to Interpret
High (>30%): Filers like Berkshire make enormous bets. Each change is a deliberate decision. Moderate (15-30%): Active managers with diversified conviction. Low (<15%): Broad mandates where individual changes carry less signal.
Norges Bank holds 1,577 positions across $935B — fewer than filers one-tenth its size. Position count alone tells you nothing about concentration.
FAQ
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