A wild-card play is a term related to futures contracts. A future is a financial contract obligating a buyer to purchase, or a seller to sell, a particular asset such as a physical commodity or a financial instrument at a predetermined future date and price.
A wild-card play exists when the contract holder maintains the right to deliver on the contract for a specified period of time after the close of trading at the closing price. This can financially benefit the contract holder if there is a shift in the value or price of the asset between the setting of the closing price and the actual delivery.
For example, the holder of a Treasury bond or Treasury note futures contract can announce his/her intention to deliver on the contract before the market closes at 2:00 pm (CST) but can delay delivery until 8:00 pm. The contract holder can take advantage of any changes in interest rates during this time to better leverage his/her position.
For more on this read, Futures Fundamentals: Strategies.
This question was answered by Katie Adams.