The historic merger of daily fantasy sports (DFS) giants FanDuel and DraftKings is facing a major roadblock after the U.S. Federal Trade Commission (FTC) have raised serious competition concerns.

Recode reported that the FTC may block the FanDuel-DraftKings merger as it believe that the combination of the DFS firms will threaten competition.

Both FanDuel and DraftKings share the largest piece of the daily fantasy market pie. The report said that the two companies will face major anti-trust roadblocks if the FTC will decide only on the effect of the merger to the DFS.

The saving grace for both FanDuel and DraftKings was the fact that it introduced other products in the recent years. Daniel Wallach, a lawyer at Becker & Poliakoff in Florida who works on gaming and sporting law, pointed out that diversification of the two firms “buttress the contention that they’re not just simply in the space for daily fantasy sports.”