Vikram Mansharmani is a hedge fund manager who has written a book about asset bubbles. In a recent interview with Fortune, he points to Sotheby’s stock as a tell-tale bubble barometer. Unfortunately, his analysis of what drove both the auction house’s stock price and the art market in recent years is a little too facile to be convincing:

Also, watch for spikes in Sotheby’s (BID) common stock prices. This also signals overconfidence.Over long periods of time the price of the art auction house has generally been around $15 to $25 a share. In 1990, it rose considerably. If you look back and listen to what they were saying about the markets at the time, it was that world record art prices were being set left and right by Japanese buyers. In 1999 we had another surge in Sotheby’s stock price driven by a couple of things. For one, we had Internet buyers, and two, Sotheby’s launched Sotheby’s.com, so it played into the mania that was going on. In 2007 we had Russian billionaires, hedge fund managers, private equity executives all driving the art markets. Sotheby’s stock price reflected that and it spiked back up. It fell back down immediately after that bubble imploded.

Today Sotheby’s stock is elevated once again and it’s being driven by Chinese art buyers.

Gold, China and Facebook: Detecting Market Bubbles (Fortune)