MIAMI — New York real estate billionaire Stephen Ross has become majority owner of the Miami Dolphins, with Wayne Huizenga retaining a 5 percent interest.

The two businessmen reached an agreement Tuesday to complete a deal forged last February. At that time Ross bought 50 percent of the franchise, Dolphin Stadium and surrounding land from Huizenga for $550 million, with an agreement that Ross would later become managing general partner.

A year ago, Huizenga said it was time for another person to take control of the franchise. At the time, the Dolphins were coming off a 1-15 season. Under the new Bill Parcells regime, they improved to 11-6 this season and made the playoffs for the first time since 2001.

Ross closed on the purchase of an additional 45 percent Tuesday. That part of the agreement received pre-approval from the NFL in October.

Huizenga, 71, became sole owner of the Dolphins in 1994. A year ago he said it was time for another person to assume control.

Ross takes over with the franchise's fortunes on the upswing. When the first phase of his purchase was completed, the Dolphins were coming off a 1-15 season, worst in franchise history. Under the new Bill Parcells regime, they improved to 11-6 this season and made the playoffs for the first time since 2001.

The sale triggers a clause in Parcells' contract allowing him to leave and still receive the $9-12 million remaining on his four-year contract. After the team lost in the first round of the playoffs, Huizenga said Parcells had decided to remain for another season.

Ross gave Parcells an endorsement Tuesday.

"I want to assure Dolphin fans that I share Wayne's same passion to win and will do everything I can to support Bill Parcells in his leadership of football operations," Ross said in a statement.

General manager Jeff Ireland, scouting players preparing Tuesday for the Senior Bowl in Mobile, Ala., was asked if he would be surprised if Parcells departed.

"Yeah, I'd be shocked," Ireland said. "Obviously that would be something that we would not like to see happen. But anything can happen in this business. This time of the year it's certainly a business, so I wouldn't be shocked at anything."

For now, Ireland said, the sale won't change the way he and coach Tony Sparano go about things.

"It doesn't really change what I do, it doesn't change what Tony does, it doesn't change what Bill does," Ireland said. "We've got to win games."

Huizenga bought 15 percent of the Dolphins and 50 percent of the stadium from team founder Joe Robbie's family in 1990. Total cost of those purchases was $168 million.

The Dolphins never reached the Super Bowl under his ownership.

"The sale represents a bittersweet moment for me, but the timing is right to complete it," Huizenga said in a statement. "I know under Steve's leadership the Dolphins are in outstanding hands. We are still a 5 percent partner in the franchise and the stadium. The Huizenga family and organization will do everything we can to support Steve and the team for the benefit of all of South Florida."

Ross, 68, made his billions as a lawyer and developer and is chairman of Related Companies, an international real estate development company. He has homes in New York and Palm Beach, and he ranked 78th in 2008 on Forbes' list of richest Americans with a net worth of $4.5 billion.

Ross attended Miami Beach High School and the University of Florida, then earned degrees from Michigan and Wayne State law school. He began his career in Detroit as a tax attorney, and the Michigan business school bears his name.

Ross was a minority partner with the New York Islanders and part of a group in 1990 that tried to bring baseball to Miami before Huizenga became founding owner of the Florida Marlins. Ross also made an unsuccessful bid for the New York Jets in 1999.

Last year Forbes Magazine valued the Dolphins at $1 billion, with a revenue stream of about $232 million.