How to read a manager page

Reported value, concentration, turnover, position age — what each statistic on a manager's page tells you.

Every manager page on this site follows the same structure, and each figure answers a specific question. Here is the tour, using the language the page itself uses.

Reported 13F portfolio value

The sum of the filing's reported position values — U.S. reportable longs only, never "assets under management." Comparing this number across quarters mixes two effects (flows and market moves), which is why the page separates position changes from value changes.

Positions and effective holdings

The raw position count overstates diversification when a portfolio is top-heavy. Effective holdings (1 ÷ HHI, the inverse Herfindahl of portfolio weights) answers: "this portfolio behaves as if it held N equal positions." A 100-position book with 60% in the top five behaves like a dozen positions, and the effective number says so.

Top-10 weight and concentration

The share of reported equity value in the ten largest positions. Above ~60% is a concentrated book where single names carry the portfolio; below ~20% is breadth, where single positions say little about conviction. Read every other statistic in light of this one — a new 0.4% position means something different at Berkshire than at a 3,000-name quant fund.

Turnover and activity

How much of the book changed since last quarter (the exact formula is on the methodology page). Low-turnover managers make quarterly snapshots trustworthy; high-turnover managers make them a blur. The New/Increased/Reduced/Exited counts show the quarter's activity in positions rather than dollars.

Position age

How many consecutive quarters each current position has been reported (within our tracked history). A book dominated by 9+-quarter positions belongs to a holder; one dominated by 0–1-quarter positions belongs to a trader.

The passive caveat

For index giants, position changes mostly reflect fund flows and index rebalancing, not views. Their pages carry a standing note; read their size, not their conviction.