The company's exclusive access to the rights from all six major Hollywood studios for the first subscription pay-TV window was found to have led to reduced choice and innovation, in addition to higher prices.
Laura Carstensen, chairman of the movies on pay-TV market investigation, said: "Sky has had control of recent movie content on pay-TV for many years.
"At the heart of the problem is Sky's strong position in the pay-TV market, with twice as many subscribers to pay-TV as all other traditional pay-TV retailers put together."
She added: "This provides Sky with a great advantage when it comes to bidding for movie rights, which no rival bidder has yet been able to overcome - and, if things stay as they are, we see no likely prospect of change."
In its provisional findings, the CC said that potential rivals are unable to bid successfully against Sky because of its large subscriber base. The CC said that while Sky supplies Sky Movies to other pay-TV outlets, this still does not let those firms compete effectively with Sky for subscribers.
The commission noted that other developments are currently taking place in the pay-TV market but said that on current evidence these would not likely diminish Sky's advantages to any "meaningful degree".
Responses have been invited and consultations have been launched on increasing competition in the market.