Fox shareholders would hold 25 percent of the new Disney, the sources told CNBC. A deal could be announced as early as Thursday, as CNBC reported earlier this week.
But there is not expected to be an announcement regarding the management of the new company, the sources said.
Shares of Fox fell 3.6 percent Wednesday morning, while shares of Disney were trading down 0.1 percent.
Disney became the sole suitor after Comcast, the parent of CNBC, dropped its bid on Monday. The two sides have talked on and off this fall. The deal is a recognition that scale is necessary to compete against Facebook, Alphabet's Google, Amazon and Netflix, which are changing consumer habits.
For Disney, it is an opportunity to add movie studio and television production assets as it readies its own direct-to-consumer offering. The Fox assets also bring significant international exposure, including its 39 percent ownership of U.K.-based Sky.
The Fox that remains after the deal is complete, including news and sports businesses, would have earnings before interest, taxes, depreciation and amortization of $2.8 billion. It would be worth $10 a share, sources told CNBC earlier this week.