I just read about net book value and thought it was interesting to share this, because honestly many investors don’t give it the importance it deserves. It’s a key concept if you really want to understand what’s happening with the companies that are listed.

Basically, when we talk about net book value, we refer to the company’s own equity resources that correspond to each share. That is, share capital plus reserves. The difference with the nominal value is that nominal value only looks at the moment the shares are issued, while net book value reflects the company’s current situation.

Many also call it **Valor en Libros**, and it’s the foundation of Value Investing. It’s that style where you look for companies whose accounting books show a value that the market is not recognizing. It sounds simple, but it requires discipline.

Now, how do you calculate this? The net book value formula is relatively straightforward: you take total assets, subtract liabilities, and divide by the number of shares outstanding. This gives you the net book value per share. For example, if a company has 3.200 billion in assets, 620 million in liabilities, and 12 million shares, the calculation would be (3.200 - 620) divided by 12 million, which gives you approximately 215 euros per share.

From this comes something very useful called the P/VC ratio, which is the market price divided by net book value. If the result is greater than 1, the stock is expensive compared to its books. If it’s less, it’s cheap. But here’s the important part: that doesn’t mean it will go up. I’ve seen cheap stocks in the books that have been falling for years because the economic context doesn’t support them.

The reality is that net book value has limitations. It doesn’t account for intangible assets, which for technology or software companies is almost everything. It also doesn’t work well with small-cap companies, which are often new and whose book value doesn’t reflect their potential. And to make matters worse, there’s what they call creative accounting, where accountants “dress up” the numbers in ways that are legal but questionable.

The most famous case here was Bankia in 2011. It went public with a 60% discount compared to its book value, and it looked like a bargain. But afterward it turned into a complete disaster; it ended up being absorbed by Caixabank in 2021. This shows that net book value is not a guarantee of anything.

So yes, knowing the formula for net book value is useful, especially if you work with fundamental analysis. But it can’t be your only criterion. It has to be one more tool in your toolbox, alongside competitiveness analysis, macroeconomic conditions, and management quality. Net book value shows you the accounting solidity at a specific moment, but the future depends on far more than that.