21st Century Fox saw Disney as a safer regulatory bet than Comcast when deciding on competing bids, a Monday filing with the U.S. Securities and Exchange Commission reveals.

The registration document states that “while a potential Disney transaction was likely to receive required regulatory approvals and ultimately be consummated, a strategic transaction with Comcast continued to carry higher regulatory risk leading to the possibility of significant delay in the receipt of merger consideration as well as the risk of an inability to consummate the transactions.”

One reason Disney was less likely to face such regulatory scrutiny, the filing says, because of its mix of businesses. Comcast, on the other hand, could have been seen as a greater threat to competition, partially due to the fact it would gain a controlling position in Hulu.

Disney’s $38 per share cash-and-stock bid, compared to Comcast’s $35 per share all-cash proposal, did not hurt, either, according to the filing.

Although the deal is expected to go through in the next six to twelve months, Disney is on the hook for $2.5 billion to 21^st Century Fox if the merger is derailed by antitrust regulation.

Disclosure: Comcast is the parent company of NBCUniversal and CNBC.