# Understanding Event Studies: Methods and Uses in Investing

## What Is an Event Study?

An event study is an empirical analysis that examines the impact of a significant [catalyst](https://www.investopedia.com/terms/c/catalyst.asp) occurrence or [contingent](https://www.investopedia.com/terms/c/contingency.asp) event on the value of a security, such as company stock.

Event studies can reveal important information about how a security is likely to react to a given event. Examples of events that influence the value of a security include a company filing for [Chapter 11](https://www.investopedia.com/terms/c/chapter11.asp) bankruptcy protection, the positive announcement of a [merger](https://www.investopedia.com/terms/m/merger.asp), or a company defaulting on its debt obligations.

### Key Takeaways

*   Event studies are crucial for understanding the impact of significant events on a company's stock value by comparing actual returns to normal or average returns.  
    
*   The methodology, often relying on the market model, utilizes statistical methods to analyze the effect of specific events through the examination of abnormal returns relative to a reference market.  
    
*   Event studies are versatile tools used in various industries, including finance and insurance, to predict reactions to events and forecast future occurrences.  
    
*   The results from event studies can help in forming macroeconomic insights by showing how industries, sectors, or markets respond to particular events.  
    

## Understanding the Mechanics of Event Studies

An event study, also known as event-history analysis, employs [statistical](https://www.investopedia.com/terms/s/statistics.asp) methods, using time as the dependent variable and then looking for variables that explain the duration of an event—or the time until an event occurs.

In [insurance](https://www.investopedia.com/terms/i/insurance.asp), event studies use time to estimate mortality and make [life tables](https://www.investopedia.com/terms/a/actuarial-life-table.asp). In business, they predict how long equipment will last or when a company might close.

> **Important**
>
> An event study, whether on the micro- or macro-level, tries to determine if a specific event has, or will have, an impact on a business's or economy's financial performance.

Other event studies, such as an interrupted time series analysis (ITSA), compare a trend before and after an event to explain how, and to what degree, the event changed a company or a security. This method may also be employed to see if the implementation of a particular policy measure has resulted in some [statistically significant](https://www.investopedia.com/terms/s/statistical-significance.asp) change after it has been put in place.

An event study conducted on a specific company examines any changes in its stock price and how it relates to a given event. It can be used as a [macroeconomic](https://www.investopedia.com/terms/m/macroeconomics.asp) tool, as well as analyzing the influence of an event on an industry, sector, or the overall market by looking at the impact of the [change in supply](https://www.investopedia.com/terms/c/change_in_supply.asp) and demand.

## Detailed Techniques in Event Study Methodology

Theoretically, a [stock price](https://www.investopedia.com/articles/stocks/08/stock-prices-fool.asp) takes into account all available information and expectations about the future. According to this theory, it is possible to analyze the effect of a specific event on a company by looking at the associated impact on the company's stock.

The market model is the most common analysis used for an event study. This methodology looks at the [actual returns](https://www.investopedia.com/terms/a/actualreturn.asp) of a baseline reference market and tracks the correlation of a company's stock with the [baseline](https://www.investopedia.com/terms/b/baseline.asp).

The market model monitors the [abnormal returns](https://www.investopedia.com/terms/a/abnormalreturn.asp) on the specific day of an event, studying the stock's returns and comparing them to the normal or average returns. The difference is the actual impact on the company. This technique can be used over time, analyzing consecutive days to understand how an event affects a stock over time.

An event study can expose larger [market patterns](https://www.investopedia.com/articles/technical/03/060303.asp). Repeating the same model with similar events helps predict usual stock price reactions.

## What Is an Event Study in Economics?

In economics and finance, an event study shows if there's a link between an event and a company's stock price or value.

## What Is a Stock Event?

A stock event is when a company's stock undergoes a change, such as a stock split, reclassification, dividend payment, stock combination, or any other event that impacts shareholders.

## What Are the Steps in Conducting an Event Study?

The first step in an event study is defining the event, then picking the companies that the event will theoretically impact. From there, normal returns and abnormal returns should be determined using various models, such as the constant mean return model, the market model, various economic models, and so on. The next step would be to measure and analyze the abnormal returns.