Damien Who? Art Sharks Swim at Their Own Risk; Flippers, Take Heed

Millions of dollars of art will be on offer at Christie's sale of postwar and contemporary work this week in London, though it's hard to say if anyone will get to enjoy it.

You know. Art?

Instead, collectors are buying works to flip them quickly for a beautiful profit, as Katya Kazakina writes in a recent article . It's the Easy-Bake oven of the art world: Buy a painting, put it in a storage locker , wait a few years -- or months -- and you've got a gold mine. Kazakina has also reported that the global art market totaled $66 billion last year, with $6.8 billion coming from auction sales of postwar and contemporary art.

Leaving aside the bigger questions (if a painter paints a painting and no one ever looks at it, was it painted?), the dazzling numbers mask a harsh reality. An index of the 50 top-selling contemporary artists compiled by the database Artnet has caught up with, and then far outstripped, the S&P 500 over the last couple of decades. But as Felix Salmon has convincingly detailed , those top 50 artists are always changing. The top 50 in 2008 are a very different bunch from those in 1988. You would have to constantly, and shrewdly, buy and sell various artists from year to year to match Artnet's results. New art is consistently a good buy, until it isn't new anymore.

In the mid-19th century, wealthy Americans gobbled up French academic painters like William-Adolphe Bouguereau, whose popularity peaked in the early 1880s. Bouguerau had a fantastic pedigree in the hallowed Academy. He "looked like the safest bet in the world," says Julia Langbein, an art historian who specializes in the 19th century. But by the turn of the 20th century, Impressionists had effectively ended his popularity. Bouguerau's decline in prestige -- and price -- was precipitous.

Or take the Futurist movement, founded in 1909 and currently the subject of a massive exhibition at the Guggenheim Museum in New York. While it enjoyed significant early acclaim, after World War II it hadfallen from favor, and pretty much stayed that way.

More recent examples abound, the most notorious of which is Damien Hirst, one of the Young British Artists of the late 1980s and early 1990s. Hirst's art, like Bouguerau's, looked fundamentally and lastingly expensive. Is that a real shark ?! Are those real diamonds ?! Works bought at the artist's peak, between 2005 and 2008, sold at an average loss of 30 percent in the next three years, and the number of Hirsts on offer at public sales has sharply declined, along with the value of the sales.

Some of these artists came back. Ninety years after his death, Bougereau was in vogue again.

That's a long time to wait. Maybe collectors should consider how their art would look on the wall. It might be there for a while.

Before it's here, it's on the Bloomberg Terminal.