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Abnormal Return


Abnormal return is a financial term that refers to the difference between an investment’s actual performance and its expected performance, given the overall market’s or benchmark’s returns. It is often used to evaluate the efficiency of a portfolio or the skill of a fund manager. A positive abnormal return suggests that an investment has outperformed the benchmark, while a negative abnormal return indicates underperformance.


The phonetic pronunciation of the keyword “Abnormal Return” is: æbˈnɔrməl rɪˈtɜrn

Key Takeaways

  1. Abnormal Return Definition: An abnormal return refers to the excess return generated by a security or investment relative to the expected return during a specified time period. This performance evaluation tool can be used to compare the actual performance of a stock, bond, or other investment to its expected performance or benchmark.
  2. Abnormal Return Calculation: To calculate the abnormal return, subtract the expected return from the actual return. Expected return takes into consideration the relevant benchmark or market index, while the actual return reflects the security’s performance over the observation period. A positive abnormal return suggests that the investment has outperformed, while a negative abnormal return indicates underperformance.
  3. Importance in Event Studies: Abnormal returns are often used in event studies to assess the financial impact of specific events or news on a security or investment. By measuring the abnormal return around the date of the event, researchers can determine if the event has a significant influence on the security’s performance, and if it did, they can measure the magnitude of this influence.


Abnormal return is an important concept in business and finance as it measures an investment’s performance relative to its expected rate of return, based on historical data or standards. This metric helps investors, analysts, and fund managers evaluate the effectiveness of their investment strategies by determining whether an asset’s returns are due to skillful decision-making or simply chance. The identification of abnormal returns can signal the need for an adjustment in strategy or portfolio diversification and can also highlight potential market inefficiencies that savvy investors may exploit. Furthermore, understanding abnormal returns aids in evaluating the performance of money managers and aids in investment decision-making process.


Abnormal return is a vital concept in the realm of finance and investing, as it serves as a critical tool to gauge an investment’s performance relative to a benchmark index or a well-accepted market model. Portfolio managers and analysts employ this metric to assess the effectiveness of their investment strategies and assess whether their portfolio is over or underperforming the broader market. By calculating the abnormal return, investors evaluate the value generated by their decision-making or active management and differentiate it from the potential gains simply due to market movement. Moreover, the abnormal return is widely used to study the impact of specific events or pieces of news on a stock or an overall portfolio. Event studies examine the abnormal returns generated in a particular time frame associated with corporate announcements, earnings releases, mergers and acquisitions, or any other market events. Researchers provide vital insights into market reactions and how new information is incorporated into asset prices. Ultimately, understanding abnormal returns facilitates a more informed investment approach, fine-tunes portfolio management strategies, and aids in identifying factors that ensure financial success.


Abnormal return is a term used to describe the difference between an investment’s actual return and its expected return, given the overall market performance or other factors. Here are three real-world examples highlighting the concept of abnormal returns: 1. Exceptional Earnings Report: A technology company (Tech Corp) releases its quarterly earnings report, showing a significant increase in revenue and profitability compared to analysts’ expectations. As a result, the company’s stock price surges 8%, while the overall stock market remains relatively flat. In this scenario, the 8% increase in Tech Corp’s stock price represents an abnormal return since its performance vastly outperformed the broader market and surpassed expectations. 2. Positive Pharmaceutical Trial Results: A pharmaceutical company (Pharma Inc) announces successful results from a crucial phase III clinical trial for a new, potentially game-changing drug. Given the positive outcome and high commercial potential, the company’s stock price soars 20% in a single day, while the industry index only gains 1%. In this case, the 19% difference represents an abnormal return for Pharma Inc’s shareholders, as it significantly outperforms the average performance within the pharmaceutical industry. 3. Merger and Acquisition: A retail company (RetailCo) announces that it will be acquired by a larger competitor at a premium to its current market price. Upon this news, RetailCo’s stock price jumps 15% in anticipation of the acquisition, while the overall market only gains 0.5%. This 14.5% differential return represents an abnormal return for RetailCo’s investors, as it exceeds the return that would have been expected given the overall market conditions.

Frequently Asked Questions(FAQ)

What is an Abnormal Return?
An abnormal return is the difference between an investment’s actual performance and its expected performance based on market conditions, risk, and other factors. It is a measure used to evaluate the effectiveness of portfolio management and the performance of individual securities.
How is Abnormal Return calculated?
The Abnormal Return can be calculated by subtracting the expected return from the actual return. In mathematical terms: Abnormal Return = Actual Return – Expected Return. The expected return can be determined using various models like the Capital Asset Pricing Model (CAPM).
What does a positive Abnormal Return signify?
A positive abnormal return indicates that the investment performed better than expected, given the level of risk and market conditions during the investment period. This could be due to several factors such as superior management, efficient operations, or favorable market conditions for the specific industry or sector.
What does a negative Abnormal Return signify?
A negative abnormal return occurs when the investment underperforms compared to the expected return based on the risk and market factors. This may be a result of poor management, adverse market events, or unfavorable changes in the industry or sector.
How is Abnormal Return used in investment analysis?
Abnormal return is a valuable metric in evaluating the performance of various investments, including stocks, bonds, and portfolios. It helps investors and portfolio managers assess the effectiveness of their investment strategies and the impact of external factors on investment performance. Additionally, abnormal returns can also be used to identify market inefficiencies or opportunities for arbitrage.
What are some limitations of Abnormal Return?
One of the key limitations of abnormal return is that it relies on the accuracy of the expected return calculation. If the model used to estimate expected returns is flawed or outdated, the calculated abnormal return may not accurately represent the investment’s true performance. Additionally, abnormal returns may not always provide clear insight into the cause of an investment’s performance, as various factors may contribute to the observed deviation from expectations.

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