That markets are less than perfectly efficient is hardly a controversial proposition; indeed, several examples of notable market efficiencies were presented to the Supreme Court this past Term when it considered the continuing vitality to the fraud-on-the-market challenge in Halliburton. Many of those examples, however, are several years old – which is why it was so amusing for me to see two new instances of dramatic inefficiencies just in the last month.
First, the New York Times published a piece, How Our Taxi Article Happened to Undercut the Efficient Market Hypothesis, explaining how publication of an article on falling medallion prices sent the stock price of Medallion Financial – a company that issues loans secured by taxi medallions – tumbling. This was surprising because information about taxi medallion prices is public, so the stock should not have been reacted to the news. Josh Barro, author of both pieces, speculates that the price drop may have occurred because some of the information in his article may have been difficult for investors to obtain, particularly since false information regarding medallion prices had been (inadvertently) circulated by the New York Taxi and Limousine Commission.
(Which, by the way, suggests that courts