Participation is a constraint, not a capacity certificate

Start with the trade, not the portfolio headline

A strategy's capital base does not determine implementation difficulty by itself. What matters is the proposed change in each holding relative to the liquidity available during the permitted trading window. A large portfolio with slow, dispersed changes can demand less liquidity per stock than a smaller concentrated strategy. Begin with position changes, not a universal assets-under-management ceiling.

Frazzini, Israel and Moskowitz's trading-cost study uses institutional execution data to examine variation across trade sizes and stock characteristics. It motivates conditioning costs on implementation circumstances. It does not supply an impact coefficient that can be transplanted into any strategy. Investor style, order urgency, security coverage and execution arrangements differ, so source-level findings are not a capacity approval.

Scale one trade explicitly

Assume a fictional stock trades $5 million per day and a rebalance requires buying one percentage point of portfolio capital. At $25 million of capital, the trade is $250,000, or 5% of daily traded value. At $100 million, it becomes $1 million, or 20%. The same weight change imposes four times the dollar demand.

Under an illustrative 5% daily participation ceiling and unchanged daily volume, the smaller order fits within one day while the larger requires at least four days. This is a planning lower bound, not an execution guarantee. Available volume may be lower, the signal may decay before completion, and competing orders can make the assumed price unattainable even when the arithmetic ceiling is satisfied.

Match the volume denominator to the window

Average daily volume is not automatically available during a short opening window or a closing auction. Use a denominator compatible with the intended schedule and security. A daily mean can also conceal a highly skewed distribution; inspect low-volume days and event periods. Keep share volume and dollar volume consistent with the order units and the price used for conversion.

Apply constraints to liquidation as well as entry. A portfolio assembled gradually may need to exit many correlated positions at once during a shock. Include concentrated holdings, trading halts and stressed volume in the scenario set. An estimated average cost curve cannot establish that a forced exit will clear at its predicted price, particularly when many participants pursue similar trades.

Capacity is a joint economic question

To evaluate capacity, combine a documented gross research opportunity with turnover, price impact, explicit costs, borrowing where relevant, and the time needed to trade. A participation screen only tests one part of that chain. Report how many trades breach the constraint, their capital share and their contribution to any result. Hiding the difficult tail behind average participation produces an incomplete assessment.

Use a small predeclared grid of capital levels and adverse assumptions. Do not select the largest level that preserves an attractive rounded return and call it verified capacity. Without observed execution evidence, describe the output as a sensitivity study. The table contains invented capital, volume and allocation inputs; it makes no claim about an actual strategy's scalable assets, available market liquidity or achievable implementation.

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Sources & reproduction

Primary references support the definitions and method. Numerical examples are illustrative unless a source record is explicitly identified.

• Frazzini, Israel and Moskowitz: Trading Costs
• NYSE: Closing Auction - Immediate Market Impact, Price Drift and Transaction Cost

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