In accounting terms, an asset is a thingy on the left-hand side of the balance sheet: it’s everything that makes up a company’s wealth.
There are two kinds:
That’s a rule from the Plan Général Comptable, France’s official chart of accounts. And article 613-1 of that same rulebook states that a player bought from another club is an asset, and that his transfer fee is capitalised.
Let’s say I own CS Sedan Ardennes, a small club from the French lower leagues. If I buy Kylian Mbappé (yeah, what of it?) for €145M, I book €145M as an asset. And I can amortise my investment over the length of his contract.
Which, incidentally, is what baffles most football fans about financial fair play (FFP). The rule says a club must not spend more money than it earns. So if I pour €500M of my own money into Sedan, it actually changes nothing about my ability to buy, unless it boosts revenue.
But since I signed Mbappé for 5 years, I amortise over the same period. So it’s €29M a year that goes into my financial fair play calculation. Not €145M.