How much do transaction costs actually drag on portfolio performance?

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AcadiFi · Accepted Answer

Transaction costs include explicit (commissions, fees, taxes) and implicit (spread, market impact, opportunity) costs. Together they create a meaningful drag that compounds over time.

A realistic institutional equity fund might run 60% annual turnover. Round-trip cost per trade might be 25 basis points (half-spread + modest impact + commission). Annual drag: 0.60 × 25 bps = 15 bps per year on net assets. Over 20 years, the compounded cost reduces a 7.0% gross return to roughly 6.85% — a terminal wealth hit of about 3%.

Small-cap or emerging-market funds with 50+ bps round-trip costs and higher turnover can lose 75–150 bps annually. A portfolio manager named Thabiso Mokoena rebalancing quarterly in a frontier market fund might see 1% of AUM evaporate purely into costs.

Components and typical sizes for a mid-cap US equity:

- Commission: 1–3 bps
- Half-spread: 5–15 bps
- Market impact: 5–30 bps (size dependent)
- Opportunity cost: variable, often 10+ bps for partial fills

Active managers must clear this hurdle before outperformance begins. A study by the Pedersen group showed net alpha for top-quartile managers shrank from 3% to below 1% once all implementation costs were deducted. This matters for FRM liquidity modules because transaction cost assumptions directly feed liquidity-adjusted VaR and liquidation-horizon calculations.

The cheapest alpha is cost reduction: the dollars saved drop straight to the bottom line.

How much do transaction costs actually drag on portfolio performance?

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