Calculate relative performance in python on daily stock price data

When working with daily stock price data, it is often necessary to calculate the relative performance of a stock. This can be done in various ways using Python. In this article, we will explore three different approaches to solve this problem.

Approach 1: Using Percentage Change

One way to calculate relative performance is by using the percentage change formula. This formula calculates the percentage change between two consecutive data points. Here’s how you can implement this approach:


# Sample code
import pandas as pd

# Load the stock price data into a DataFrame
data = pd.read_csv('stock_data.csv')

# Calculate the percentage change
data['Relative Performance'] = data['Close'].pct_change() * 100

# Print the result
print(data['Relative Performance'])

This approach calculates the relative performance as the percentage change between consecutive closing prices. However, it does not take into account any other factors that may affect the stock’s performance.

Approach 2: Using Log Returns

Another way to calculate relative performance is by using log returns. Log returns are calculated by taking the natural logarithm of the ratio between two consecutive data points. Here’s how you can implement this approach:


# Sample code
import pandas as pd
import numpy as np

# Load the stock price data into a DataFrame
data = pd.read_csv('stock_data.csv')

# Calculate the log returns
data['Relative Performance'] = np.log(data['Close'] / data['Close'].shift(1))

# Print the result
print(data['Relative Performance'])

This approach calculates the relative performance as the log returns between consecutive closing prices. Log returns are often preferred over percentage change as they are additive and have desirable statistical properties.

Approach 3: Using Rolling Window

A third approach to calculate relative performance is by using a rolling window. This involves calculating the relative performance over a specified window of time. Here’s how you can implement this approach:


# Sample code
import pandas as pd

# Load the stock price data into a DataFrame
data = pd.read_csv('stock_data.csv')

# Set the rolling window size
window_size = 5

# Calculate the relative performance using a rolling window
data['Relative Performance'] = data['Close'].rolling(window_size).apply(lambda x: (x[-1] - x[0]) / x[0] * 100)

# Print the result
print(data['Relative Performance'])

This approach calculates the relative performance as the percentage change over a rolling window of closing prices. It provides a more smoothed out view of the stock’s performance over time.

After evaluating these three approaches, it can be concluded that the second approach, using log returns, is the better option. Log returns are widely used in finance and have desirable statistical properties. They provide a more accurate representation of the stock’s performance compared to the other two approaches.

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17 Responses

  1. Approach 2 seems more accurate to me, but approach 3 sounds intriguing. What do you guys think? #stockmarket

    1. I disagree. Approach 1 (Using Simple Returns) is simpler and easier to understand. Accuracy is subjective and both methods have their merits. It ultimately depends on the specific context and preferences. What matters is choosing the approach that suits your needs.

    1. I couldnt agree more! Approach 2 with log returns is a game-changer. Its refreshing to see a different take on calculating stock performance. Now, lets hope it translates into actual gains in the market! 🤞🏼

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