An odd change in the markets since my first Predictwise post ten days ago. According to Predictwise the probability that a republican candidate gets a majority of the delegates has dropped from 50% to 38%. The odds that the convention goes into at least a second round has increased from 42% to 55%. Meanwhile the probability of Trump’s nomination has stayed relatively steady, dropping slightly from 78% to 76%. If you compute the conditional probability (a little risky), then Trump still has at least a 56% chance of winning the nomination after failing to win in the first round of voting.

Why the change? If you believe the numbers I see two reasons: Perhaps the market thought Cruz had a chance of winning a majority of the candidates before and now after some Trump victories that chance has dropped. Or maybe the market thinks Trump is better prepared to navigate a win at the convention.

Either way it may be time to brush up on the minutiae of Republican delegate and convention rules. As the Associated Press put it this morning “in a campaign season so far defined by extraordinary insults and extreme rhetoric, the 2016 Republican presidential nomination fight could ultimately be decided by lawmakers, party activists and lawyers.”

Lance Fortnow is a professor and chair at the School of Computer Science at the Georgia Tech College of Computing