Here's a tweet that Show sent yesterday:
There are no longer any Big Show/Shaquille O'Neal WrestleMania prop markets available. They were taken down over the summer when Big Show 'confirmed' to TMZ that a meeting between the pair would take place at Mania 33.
Betfair.com published a market in early April, shortly after Shaq made a surprise appearance in the Andre the Giant Memorial Battle Royal at WrestleMania 32, where customers could bet on him being in an official match at the following years event. I strongly recommended placing a bet on the 'Yes' throughout the entire time the market was available because WWE has wanted to have a Big Show versus Shaquille O'Neal singles match for many years.
It also makes sense when acknowledging that WrestleMania 33 is set to take place in the city where O'Neal first started his professional basketball career - Orlando.