The value of a Picasso or a Ferrari typically rises in a strong economy, as do shares in a consumer staple like Procter & Gamble.

But when the economy sours, those shares may be easier than the other possessions to shed. As wealthy collectors pull back on extravagances, investors could get stuck holding an asset they might have to unload at a loss.

In 2012, when the market was roaring for passion assets — those in which you put money where your heart is — I wrote a series of columns on why people invested in things like vineyards, racehorses and sports teams.

This time, I will look at five nontraditional asset classes that are popular with wealthy investors and with an eye on what to expect in a market downturn. Art is the first of five valuable but illiquid assets I plan to examine in the coming weeks. The others are cars, collectibles like wine and jewelry, private equity and real estate.