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Strategy #0000000082 · Calendar effects and seasonality

Calendar-month return seasonality
Enter same-month history, off-season comparison return and costs for a simplified scenario spread.

Seasonality strategies compare a stock’s historical returns in the same calendar month with other months. Heston and Sadka document persistent calendar-month patterns; explanations include cash flows, investor behaviour and seasonal risk. Multiple testing, data mining, month selection and trading costs can inflate in-sample results.

Beginner-friendlyAbout 8 minutesEvidence and practical analysis

Three ways in

Understand the story. Then inspect the risk.

Start with a familiar situation, check the payoff, then test how the numbers change.

The idea · in two minutes

What assumed return spread separates a recurring calendar month from off-season periods?

Seasonality strategies compare a stock’s historical returns in the same calendar month with other months. Heston and Sadka document persistent calendar-month patterns; explanations include cash flows, investor behaviour and seasonal risk. Multiple testing, data mining, month selection and trading costs can inflate in-sample results.

Enter same-month history, off-season comparison return and costs for a simplified scenario spread.

Seasonality varies across samples and markets; selecting the best-performing month creates data-mining bias.

  • Signal metricEnter same-month history, off-season comparison return and costs for a simplified scenario spread.
  • Return scenarioSeasonality varies across samples and markets; selecting the best-performing month creates data-mining bias.

Illustrative research examples only. They are not live signals or a recommendation.

Variants · same family, different risk levers

Related approaches use different horizons and data.

Compare ranking rules, holding periods and cost assumptions.

Related strategyRelationshipWhat changesNew cost or risk
Core versionSignal sortSeasonality strategies compare a stock’s historical returns in the same calendar month with other months. Heston and Sadka document persistent calendar-month patterns; explanations include cash flows, investor behaviour and seasonal risk. Multiple testing, data mining, month selection and trading costs can inflate in-sample results.Seasonality varies across samples and markets; selecting the best-performing month creates data-mining bias.
Industry-neutral versionRelative rankingCompare firms within similar industries.Classification and small samples affect signals.
Multi-signal versionFactor combinationCombine with quality or liquidity signals.Adds weight, collinearity and data-mining risk.

Seasonality varies across samples and markets; selecting the best-performing month creates data-mining bias.

Read beyond the summary

References

Primary sources and research used to describe the strategy and its limits.

  1. 01Heston & Sadka (2008), Seasonality in the Cross-Section of Stock Returnsresearch