commodities (the normative and generally accepted economic definition) are kinds of assets that are fungible, that is, they have a high level of standardization so that one object can be replaced for like; they are, in theory, interchangeable goods and services, by definition. Assets more generally are real property that should, in theory, have positive value (if its negative, its called a liability, and yes, art can be a liability ) and could be exchanged for cash, however, they do not automatically bare liquid cash flow, and cannot be exchanged for like, ie, a typical asset such as a house does not present income/profit except at point of sale and not as a matter of simple ownership over time. Likewise, one cannot simply trade one house for the next, evenly. That said, positive value could be leveraged into, in the case of a house, a loan. Like loans, certificates, bonds, shares, options, etc., are, when owned, an asset class normally refereed to as 'financial instruments', which on occasion have things like dividends (income) as part of the contractual agreements related to the interest and other rules defined by the instrument itself--this is not standardized. If you are managing a larger portfolio, that does include some artworks (which is the scale they are ostensibly talking about here with multimillion dollar paintings) holding some liabilities could make sense to offset things like taxes on other assets, instruments, etc…. depending on how good your account and lawyer is. You are correct, art is an exceptional asset of its own class, however, expensive artworks exist in an unregulated market which basically allows for various forms of manipulation... often, but not limited to, repackaging the potential liquid value of the work 'if it were sold' (mark to market accounting, usually twined with price-fixing). This is not the sin qua non of why prices go up, but there are some very tangible incentives for how high roller art can function as a part of or as a mechanism for what is called private wealth management...which also includes things like tax sheltering and laundering—which is the real pickle, at present, how fancy do you want accounting to be? The question of authorship deals with brands and trademarks in general as well, and the question is not only if a Richter has a 'stamp' on it..even like Richters are not evenly exchangeable, ie, they don't qualify as commodities even when official. If we're on the lower-end of the scale, it's just a 'good' usually called a 'collectable'.