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Understanding the Weekend Effect in Stock Markets

Nupur Wankhede

The weekend effect refers to a curious stock market pattern where returns on Mondays tend to be lower than those on the preceding Fridays. This phenomenon has intrigued analysts and economists for decades, raising questions about behavioural patterns, institutional trading, and market efficiency.

What Is the Weekend Effect

The weekend effect is a well-documented market anomaly where average stock returns on Mondays have historically been lower—or even negative—compared to other weekdays, particularly Fridays. This observed pattern reflects a historical divergence in weekday returns

This effect was first identified by economist Frank Cross in 1973, who analysed returns on the New York Stock Exchange and found a consistent drop in prices on Mondays. The anomaly gained attention because it contradicted the efficient market hypothesis, which states that asset prices should reflect all available information.

Several theories attempt to explain the phenomenon, including investor psychology, weekend news spillover, institutional trading behavior, and lower trading volumes on Mondays. While the effect has diminished in recent years, it remains a key example in behavioural finance.

Historical Evidence of the Weekend Effect

The weekend effect was first empirically observed by economist Frank Cross in 1973, who noted that average stock returns on Mondays were significantly lower than those on other trading days—particularly Fridays. Cross’s findings, based on data from the New York Stock Exchange (NYSE), showed that while Friday returns were often positive, Mondays exhibited frequent losses, despite no fundamental reason for such a pattern.

This anomaly gained further credibility during the 1970s and 1980s, as additional academic studies confirmed consistent negative Monday returns across various indices, including the S&P 500. Researchers pointed to investor pessimism over the weekend, delayed reaction to news, and institutional trading patterns as potential causes.

However, by the mid-to-late 1970s, and increasingly into the 1990s, evidence suggested that the weekend effect was diminishing in magnitude. The rise of automated trading, greater market awareness, and improved information flow reduced arbitrage opportunities. According to ASU research and Investopedia, the anomaly has become far less pronounced, although remnants of the effect still appear in certain markets and small-cap stocks.

Recent Analysis and Variability

Recent data reveals that the weekend effect is no longer consistent. Key findings:

  • Its magnitude has declined over time due to market efficiency improvements.

  • The pattern now varies across decades, asset classes, and regional markets.

  • Algorithmic trading and increased global market connectivity may have further diluted its impact.

Still, some researchers argue it persists subtly in specific market caps or geographies.

Why Stock Markets Are Closed on Weekends

Stock exchanges remain closed on weekends primarily for market stability and operational efficiency. Reasons include:

  • Risk mitigation: Allows time to process trades and news events.

  • Illiquidity concerns: Fewer participants are active on weekends.

  • Technical resets: Clearing systems, settlements, and IT infrastructure often undergo maintenance.

  • Work-life balance: Human traders, brokers, and regulators require downtime.

These closures also align global exchanges around a 5-day trading week norm.

Do All Markets Follow the Same Weekend Schedule

Not entirely. While most major markets (like NYSE, LSE, NSE, and ASX) operate Monday to Friday, some exceptions exist:

  • Tel Aviv Stock Exchange: Sunday to Thursday

  • Middle Eastern exchanges: Typically follow a Sunday–Thursday workweek

  • Islamic markets: May adjust for religious observances or regional schedules

These differences affect global market overlap and trading volumes on certain days.

Weekend Effect: Myth or Anomaly

The weekend effect continues to spark debate:

  • Some consider it a genuine anomaly rooted in behavioural finance.

  • Others argue it’s a mythical relic—an outdated artefact diminished by real-time trading, 24/7 news cycles, and globalisation.

  • Its persistence in emerging markets suggests market maturity may play a role.

Consensus leans towards the effect being weaker but not entirely gone—it may now depend on market structure, investor demographics, and external shocks.

Conclusion

The weekend effect offers an intriguing lens into market psychology, but its influence has waned over time. While historically significant, today’s sophisticated markets and continuous news flow have diluted its impact. Still, it remains a relevant topic for understanding the evolution of market behaviour.

Disclaimer

This content is for informational purposes only and the same should not be construed as investment advice. Bajaj Finserv Direct Limited shall not be liable or responsible for any investment decision that you may take based on this content.

FAQs

How does the weekend affect stocks?

Historically, Monday stock returns tended to be lower than those on Fridays—this was called the weekend effect.

Why do stock markets remain closed on Saturdays and Sundays?

Weekend closures help maintain liquidity, allow for operational resets, and reduce the risk of thin or volatile trading periods.

What is the impact of the weekend effect on Monday trading?

In some markets, Monday may still exhibit lower returns due to pent-up sentiment or delayed reaction to weekend news, but the effect is less consistent today.

Has the weekend effect disappeared?

Not entirely—it has weakened significantly and is now inconsistent across time and geography, though still observed in some contexts.

Hi! I’m Nupur Wankhede
BSE Insitute Alumni

With a Postgraduate degree in Global Financial Markets from the Bombay Stock Exchange Institute, Nupur has over 8 years of experience in the financial markets, specializing in investments, stock market operations, and project management. She has contributed to process improvements, cross-functional initiatives & content development across investment products. She bridges investment strategy with execution, blending content insight, operational efficiency, and collaborative execution to deliver impactful outcomes.

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