Buy Stocks on Sale: Mastering the Margin of Safety

The margin of safety is a key investment principle which refers to investing in assets significantly below their true value. If you are new to investment, keep reading to find out how to identify stocks and other assets below their intrinsic value.

how to work out margin of safety

What is margin of safety?

The margin of safety is a common principle in value investing. This concept was originally introduced by Benjamin Graham, often referred to as the father of this investment strategy. Graham elaborated on this concept in his two main books, namely “Security Analysis” and “The Intelligent Investor.”

The purpose of the margin of safety is to assess the price of a particular asset. To calculate it, we consider the trading price of the asset in the market, which is essentially its current stock market value, and compare it to its intrinsic value.

The intrinsic value is the real value of the asset, which is often estimated rather than precisely determined. By contrasting the market value with the estimated intrinsic value, we can determine whether a stock is appropriately priced, overvalued, or undervalued.

In simpler terms, the margin of safety is determined by the gap between the market value and the estimated intrinsic value. The larger this gap, the greater the margin of safety, which means there's more room for the asset's price to fall before becoming a risky investment. Therefore, a wider margin of safety provides investors with more confidence because, even in the face of market fluctuations and uncertainties, the market price would still be above the estimated intrinsic value.

However, one challenge with using this indicator is that calculating the intrinsic value of a stock is a complex task and typically results in an approximation rather than an exact figure. To estimate the intrinsic value, investors often analyse various financial ratios such as solvency, liquidity, profitability, and other relevant factors related to the company's financial health. In other words, investors use fundamental analysis to find the intrinsic value of a stock.

What is the margin of safety used for in the stock market?

The margin of safety is a critical concept in the stock market. It helps us determine whether a stock's market price is above, below, or equal to its actual intrinsic value, which is the value a share should have based on a comprehensive analysis of the company, including its financial ratios and other relevant indicators.

When we use this measure and have both the trading value (market price) and the intrinsic value of a share, we can arrive at one of three conclusions:

  1. Expensive share (overvalued) If the market value is higher than the intrinsic or real value, the share is considered expensive. In other words, it's overvalued by the market.
  2. Fairly priced share: When the market value is close to the intrinsic value, the share is considered to be fairly priced or well-valued. This suggests that the market price aligns well with the actual value of the share.
  3. Cheap share (undervalued): If the market value is lower than the intrinsic value, the share is considered cheap. In this case, it's undervalued in the market.

How to calculate the margin of safety?

Calculating the margin of safety for an asset, when we have the trading price and the intrinsic value, is a fairly simple task.

The formula to calculate it is as follows:

Margin of safety = [1 – (market price / intrinsic value)] x 100

The result gives you the margin of safety as a percentage. A positive percentage indicates that the market price is below the estimated intrinsic value, providing a buffer. The higher the percentage, the larger the margin of safety, implying a potentially safer investment.

If the margin of safety percentage is negative, it indicates that the market price of the stock is higher than your estimated intrinsic value. In this scenario, the stock is trading at a premium compared to what you believe it's actually worth.

Example of margin of safety

Let's see an example of how to calculate the margin of safety. We will consider a theoretical company, ABC.

Let's assume that after your analysis, you estimate the intrinsic value of ABC Ltd. to be £50 per share. This value is based on your assessment of the company's financial health, growth prospects, and other relevant factors.

Currently, ABC Ltd. is trading at £40 per share in the stock market.

This means that:

Margin of safety = [1 – (40/50)] x 100 = 20%

The margin of safety for ABC Ltd. is 20%. This means that the market price of ABC Ltd. is 20% below your estimated intrinsic value.

This 20% acts as a buffer or cushion. It suggests that even if your estimation of the intrinsic value is slightly off, or if the market price of the stock decreases, you have a 20% buffer before your investment starts to lose its principal value based on your intrinsic value estimate.

A 20% margin of safety is considered substantial by many value investors, indicating that ABC Ltd. might be a less risky investment according to this criterion.

Learn more about stock analysis:


The margin of safety in stock investment is a fundamental concept that serves as a buffer to protect investors from loss and uncertainty. Originating from the principles of value investing, it involves purchasing stocks at a price significantly lower than their estimated intrinsic value.

This difference, expressed as a percentage, indicates the degree of safety an investor has against potential market volatility or errors in valuation. While it doesn't eliminate risk, the margin of safety is a valuable tool for making more informed and cautious investment decisions, especially valuable in uncertain or fluctuating markets.


Can the margin of safety eliminate investment risk?

No, the margin of safety cannot eliminate investment risk entirely; it simply reduces the potential for loss by providing a buffer but does not guarantee against all types of risk.

Is a negative margin of safety bad?

A negative margin indicates the stock is priced above its intrinsic value, implying higher risk and potential overvaluation.

Is the margin of safety relevant for all types of stocks?

It's most relevant for value investing; growth investors might accept lower or negative margins, expecting future growth.

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