Buried in a US News story on art as an investment is some pretty astonishing stuff from Michael Moses of the Mei Moses Art Index which uses repeat sales to measure art asset values.

The assumption has always been that the the rise in art asset values during the overall economic slump of the global credit crisis was an anomaly. But Moses claims here that over the long term there is no correlation between art prices and financial asset prices:

The broad art market has provided compound annual returns of 5.7 percent in the last 30 years and 8.8 percent for the last 60 years, says Michael Moses, founder of consulting firm Beautiful Asset Advisors.

Better still, the index of broad art market prices is uncorrelated with those of other asset classes, such as stocks or bonds. “The stock markets went down in 2008 and our indexes were flat to a little up in 2008,” he says. The art indices “dropped substantially in 2009,” as the stock market rebounded. He pegs the long-term correlation at close to zero. That lack of correlation reduces overall volatility when art is part of a larger portfolio. The lower the volatility, the lower the risk. How much art should be in a portfolio? Moses says it depends on individual circumstances, but 10 to 20 percent is reasonable.

Why Fine Art Can Beautify Your Portfolio (US News)