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When Stop-Loss Orders Help and When Price Gaps Undermine Them

Article Quant Q&A · Author: Erick
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Summary

The discussion considers whether applying stop-loss rules to a diversified stock portfolio can reduce losses during a market crisis. It contrasts a prolonged, relatively orderly decline with a sudden market break. In the former case, stops may trigger as prices fall over time; in a sharp gap, the execution price can be far below the stop level, and thin or disrupted liquidity can make the realized loss larger than expected.

The response uses the 2008 decline as an example of a long drawdown and the 1987 crash as an example of an abrupt one-day collapse accompanied by very wide spreads and market makers withdrawing. It also points to research on optimal trading with trailing stops, but does not summarize that paper’s model or findings. The examples illustrate that stop-loss effectiveness depends on the path of prices and execution conditions. They do not establish a universal portfolio outcome or specify stop placement, trading costs, or how simultaneous stops across holdings would affect results.

Key ideas

  • Stop-loss rules may reduce exposure during a gradual and sustained market decline.
  • A price gap can cause execution well beyond the chosen stop level.
  • Liquidity disruption and wide spreads can worsen realized exits during a crash.
  • The examples highlight path and execution risk but do not establish a universal result.

Tags

EquitiesRisk managementExecution
Full text
# Stop-Loss strategies


# Stop-Loss strategies












Does anyone know some bibliography about the problems or limitations of using Stop-Loss strategies in a portfolio?

Let me explain better: for example you can have a portfolio of 30 stocks from different securities and you can put a Stop-Loss Strategy over them, but what would happen if suddenly there is a crisis like the one of 2008? Does this strategy really help you to minimize your losses?

Thank you in advance your the help!

## Answer by Bob Baerker (score 1)

https://quant.stackexchange.com/a/57385

There are lots of articles on the web about stop loss orders which explain the advantages and disadvantages.

Stop loss orders would clearly have helped "you to minimize your losses" in 2008 because for the most part, the decline was organized and took 15 months or so for the market to drop 50% and reach the bottom.

Where stop losses fail is when there are large gaps. An extreme example would be 1987 when the DJIA lost 22% in one day, bid/ask spreads were as much as several dollars wide and market makers walked away from their responsibilities.

## Answer by jason m (score 0)

https://quant.stackexchange.com/a/49814

This paper may be helpful. Generally, this is not a simple problem.

> Leung, Tim and Zhang, Hongzhong, Optimal Trading with a Trailing Stop (February 18, 2019). Applied Mathematics and Optimization, to appear, 2019, Available at SSRN: https://ssrn.com/abstract=2895437 or http://dx.doi.org/10.2139/ssrn.2895437

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