The Principal Component Analysis or PCA is a statistical technique for reducing the dimension of a large dataset.

It does it by transforming the dataset into a new set of variables, the principal components, which are uncorrelated, linear combinations of the initial variables and represent the most important part of the variability of the data.

PCA is a popular method for analysing a large dataset, reducing dimensionality, increasing the interpretability of the data by retaining essential information.

In this 7-minute video we give an introduction to PCA: https://youtu.be/YlbQoiw5ThE

In this 10-minute video we look at the maths behind the PCA with some example in Python: https://youtu.be/P0uPDcg1y_I

It finds broad applications such as data compression, classification, regression, data visualization, feature extraction, data preprocessing to gain in efficiency…

And it is used in various domains such as data analysis, machine learning, signal processing, biology, or finance.

Here is a non-exhaustive list of possible applications in finance:

**Portfolio Management**

By applying PCA to historical price data of various securities, one can identify the principal components that explain the majority of the portfolio’s variance. This information helps portfolio managers to construct portfolios with reduced risk and improved diversification.

**Risk Management**

By examining historical financial data, such as stock returns or interest rate movements, PCA can identify the primary sources of risk within a financial system. This information is valuable for estimating and managing risk exposure in portfolios, as well as for stress testing and scenario analysis.

**Factor Models**

By applying PCA to a large dataset of variables, such as economic indicators or financial ratios, one can identify the principal components that capture the most relevant information. These components can then be used as factors in the model, aiding in understanding and predicting portfolio performance.

**Portfolio Clustering**

PCA can be used for portfolio clustering, where similar assets or portfolios are grouped together based on their characteristics. By applying PCA to historical financial data, the most important sources of variation are captured and represented as principal components.

**Hedge Ratio Calculation**

PCA can be used to calculate the hedge ratio, representing the optimal proportion of an asset in a basket to neutralise the first or the first two principal components.

**Fair Value and Relative Value Strategies**

PCA can be used to calculate fair value of asset prices estimated from the first principal components and building relative value strategies buying the cheapest ones and selling the richest ones.

**Yield Curve Modeling**

PCA can be used for yield curve modeling, by analysing historical yield data for different maturities and identifying the principal components that explain the majority of the variability. The retained principal components are then used to reconstruct the full yield curve, providing insights into its shape and dynamics.

Below are several interesting articles on the topic:

Principal Component Analysis for Stock Portfolio Management, Giorgia Pasini, Department of Computer Science University of Verona, 2017.

Generating market risk scenarios using principal components analysis: methodological and practical considerations, Mico Loretan, Federal Reserve Board, 1997.

PCA for yield curve modelling, David Redfern, Douglas McLean, Moody’s Analytics, 2014.

Statistical Arbitrage in the U.S. Equities Market using ETFs and PCAs, Marco Avellaneda, Jeong-Hyun Lee, 2008.

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