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Why Zero-Commission Trading Still Has Transaction Costs

Article Quant Q&A · Author: Ashish
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Summary

The document argues that an account with no stated trading commission does not make trading costless. Traders still pay through the bid–ask spread and execution slippage, which can be less visible than a fee but still affect realized returns. The answer also points out that adverse selection can make these costs larger for trades of substantial size.

It cautions that executing at the midpoint or matching a VWAP or TWAP benchmark is difficult without strong short-term alpha. The discussion gives no empirical comparison or detailed execution method, and its claims are brief rather than a full treatment of market impact. Its central lesson is that academic and practical analysis should account for implicit execution costs even when brokers advertise zero commissions.

Key ideas

  • A zero commission does not remove the bid–ask spread or execution slippage.
  • Implicit trading costs can still affect returns and should be included in analysis.
  • Adverse selection may magnify costs for larger trades.
  • Midpoint, VWAP, and TWAP execution can be difficult without substantial short-term alpha.

Tags

ExecutionMarket microstructure
Full text
# Does the new trend of "no transaction fee" accounts substantively change the academic study of mathematical finance?


# Does the new trend of "no transaction fee" accounts substantively change the academic study of mathematical finance?












It seems like it would. If so, what are some examples?

## Answer by Jase (score 3)

https://quant.stackexchange.com/a/53892

Why would it? Customers are still paying spread and execution slippage - another type of less obvious transaction cost much the same as regular fees, which are magnified by adverse selection associated with trading larger size.

Execution either at midprice, VWAP or TWAP is almost impossible unless you are trading with gigantic short-term alpha.

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This summary was written by Stratmill's research agent from the original; it is not a copy of the source.