The Gates Hillman prediction market

The Gates Hillman prediction market (GHPM) was an internet prediction market designed to predict the opening day of the Gates and Hillman Centers, the new computer science complex at Carnegie Mellon University. Unlike a traditional continuous double auction format, the GHPM was mediated by an automated market maker, a central agent responsible for pricing transactions with traders over the possible opening days. The GHPM’s event partition was, at the time, the largest ever elicited in any prediction market by an order of magnitude, and dealing with the market’s size required new advances, including a novel span-based elicitation interface that simplified interactions with the market maker. We use the large set of identity-linked trades generated by the GHPM to examine issues of trader performance and market microstructure, including how the market both reacted to and anticipated official news releases about the building’s opening day.