Is Sotheby's Stock Sustainable?

The Wall Street Journal is wondering about Sotheby’s stock price, which has doubled in the last six months to $33:

Investors have quickly jumped into Sotheby’s stock, now at its highest level in two years. That is enough to make it appear pricey, at about 30 times 2010 consensus earnings.

There still may be time to bid. Analysts appear too cautious, estimating sales will rise only about 20% in the second half. But after a less-severe downturn ending in 2003, Sotheby’s sales jumped 60% in 2004. A similar increase in sales this year implies the stock is trading in the teens as a multiple of earnings, well below the average of 20 to 25 times during the art boom last decade.