The person on the other side of the trade. This would be the person who wrote the puts in this case and the entity harmed is more than likely the market maker

The person on the other side of the trade. This would be the person who wrote the puts in this case and the entity harmed is more than likely the market maker for Equifax. If he just shorted the traditional way by borrowing and selling the stock, then its hard to argue who he harmed.