One way the Father of Value Investing, Benjamin Graham, teaches us to know if a stock is undervalued or not, in his book Security Analysis, is looking at the liquidation value. $BRK.B
If you liquidate a business, it means selling all the assets of a business and then repaying all the liabilities. What's left is the Liquidation Value. That's just in theory. In practice, this is not. This is only the book value.
Book value is not liquidation value because you cannot really sell goodwill and some intangible assets. Then, maybe we should look at tangible book value. Once again, there are some issues such as the inability of selling depreciating assets that fast.
One way one could find the liquidation value is to estimate all the depreciation rates for each asset but that's a little too complicated. Benjamin Graham came up with a very good approximation, the net current asset value. Net current asset value is the total current assets of a company minus the total liabilities of the company. If the stock price is trading below than net current asset value, according to Benjamin Graham, it is trading under its liquidation value and might be a good investment.
These stocks are rare but if you know where to look, you can still find them. Currently, I have Qudian $QD trading under its liquidation and in the past, I had GameStop $GME trading under its liquidation value.