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"Calendar effect refers to the phenomenon observed in financial markets where the returns or performance of an asset or market exhibit recurring patterns based on the time of year or specific dates within a calendar."
What is Calendar Effect?
These patterns are not necessarily explained by fundamental or economic factors but instead reflect historical market tendencies that tend to repeat over time.
There are several well-known calendar effects in financial markets. Some examples include:
It's important to note that calendar effects are considered market anomalies and may not persist or be reliable in the future. Market conditions, investor behavior, and other factors can change over time, potentially affecting the strength or existence of these patterns.
Here's an example of a calendar effect, specifically the January Effect, using hypothetical numbers:
Suppose you are analyzing the historical returns of a particular stock index over several years. By studying the data, you notice a recurring pattern where the stock index tends to experience a significant increase in January compared to other months. You decide to investigate further and calculate the average returns for the month of January versus the average returns for the remaining months.
Here are some hypothetical numbers to illustrate the effect:
Year | January Returns (%) | Average Returns for Other Months (%)
2018 | 5 | 2 2019 | 4 | 1 2020 | 7 | 3 2021 | 6 | 2 2022 | 5 | 1
Based on this data, you calculate the average January returns to be (5 + 4 + 7 + 6 + 5) / 5 = 5.4%. The average returns for the remaining months (February to December) are (2 + 1 + 3 + 2 + 1) / 5 = 1.8%.
This hypothetical example demonstrates the January Effect, where the average returns for January (5.4%) are higher than the average returns for the other months (1.8%). While the numbers are made up for illustrative purposes, it highlights the observed pattern of higher returns during January compared to the rest of the year.
It's important to note that calendar effects can vary in strength and persistence over time, and this example does not guarantee the continued existence or predictability of the January Effect in real-world markets.