Fantasy sports websites DraftKings Inc. and FanDuel Inc. have failed to settle a raft of consumer class actions, setting the stage for a fight over arbitration.

Both websites allow players to create their own fantasy teams and win prize money based on the performance of real athletes. More than 80 class actions alleged the companies committed “insider trading” by allowing their employees to participate in contests using nonpublic information, or they enticed consumers to participate in illegal gambling.