So, what price should a buyer pay to acquire a listed company - in whole or in part? By extension, is this price - and the resulting valuation - fair, exorbitant or, on the contrary, enticing?

The two concepts of market capitalization and enterprise value come into play here. To cut to the chase: market capitalization is the valuation of a company's equity, i.e. the share that goes to shareholders; enterprise value is the sum of this equity and net debt, in other words the share that goes to creditors.

The premise is simple and common sense: when you acquire an asset - a business, a building, etc. - you also assume all the debts that go with it. - At the same time, you assume all the debts associated with it, which you will now have to repay or refinance.

In this respect, enterprise value - i.e. market capitalization plus net debt, which must also include any long-term provisions - is a more relevant "price tag" than market capitalization alone.

When a company is debt-free and has no excess cash, its market capitalization and enterprise value are more or less identical. See, for example, The Descartes Systems Group reaches for the top.

When a company is debt-free but retains a large cash surplus, its market capitalization is higher than its enterprise value.

When a company carries substantial net debt, its market capitalization is much lower than its enterprise value. 

In cases where debt is colossal and the company's solvency in serious jeopardy, shareholders' equity is typically worth next to nothing, as shareholders stand to lose everything; enterprise value, on the other hand, is very high, as creditors have de facto seized the assets. 

For companies whose debt refinancing is not a concern - for example, those that are highly profitable and enjoying sustainable growth - a valuation based on market capitalization alone makes sense.

For companies whose debt refinancing is subject to a variety of more or less acute concerns - for example, those that find themselves in the grip of delicate economic conditions despite being mediocrely profitable - it is imperative to establish a valuation model based on their enterprise value. See, for example, Boeing: Programmed Suffocation.