In the three decades since Alan Stillman opened the first Smith & Wollensky steak house in Midtown Manhattan, his empire has grown to 13 restaurants, and in 2001, it went public as the Smith & Wollensky Restaurant Group.

This week, shareholders approved a deal to sell the restaurant group to Patina Restaurant Group for $94.6 million, or $11 a share. Under the deal, the group will no longer own the eight Smith & Wollensky restaurants outside of New York City, but Mr. Stillman will retain ownership of the Smith & Wollensky restaurant on Third Avenue, as well as his four other New York-based eateries, Maloney & Porcelli and Quality Meats in Midtown, and Post House and Park Avenue Summer on the Upper East Side.

The sale was motivated not by money, but by the rigors and regulations of being publicly traded company, which “can stifle the entrepreneurial and creative edge,” Mr. Stillman said in an interview with The New York Sun.

Following the transaction, Mr. Stillman and his 27-year-old son, Michael, will form a new privately held company, Fourth Wall Restaurants, of which Michael will serve as president. The new company will focus on expanding its presence in New York. “I’d love to do something downtown,” Michael Stillman, said in an interview

“I think we’ve come full circle now,” Alan Stillman said of his son, who studied art and political theory at Brown University. “This gets Michael back to his roots.”

When Michael Stillman first expressed a desire to work in a restaurant several years ago, his father said “Great — go get a job!” He did, first at Rubicon in San Francisco, then at Tabla in New York’s Flatiron district. He learned the basics from the ground up. He also learned that he loved restaurants. He entered the family business just as it was expanding, opening up eateries in cities such as Houston and Boston.

Manhattan Ocean Club, a Smith & Wollensky Restaurant Group operation, presented the younger Mr. Stillman with his first opportunity to create something new. After 22 years, the Midtown seafood standby got a new chef, Craig Koketsu, and subtle redesign. “We were happy with everything, but it was time to turn the page,” Michael Stillman said.

That restaurant at West 58th Street became Quality Meats, and opened in 2006. It was Michael’s concept, Mr. Koketsu’s menu, and the design team AvroKo’s decor in the old Manhattan Ocean Club space. It turned out to be a winning combination of downtown edginess and its own version of chophouse fare. It was recognizable enough to please the Midtown diners, yet drew a new, younger clientele.

“I think it has been our involvement that has helped mark the changing of the guard,” explained the principal of the downtown design firm AvroKo, Adam Farmerie, said. As a resident of the Lower East Side, Michael Stillman had discovered AvroKo’s designs at neighborhood spots, and was instantly captivated by the designs.

The two companies discussed working together for a few years before finding a project. “We had to learn the subway system, and get our passports out to cross 14th street,” Mr. Farmerie said.

The Stillmans’ current project Park Avenue Summer on the Upper East Side is, perhaps, the most ambitious restaurant in New York City. It opened in June and is a re-invention of the Stillmans’s 15-year old Park Avenue Café, as well as a sort of tribute to the Four Seasons restaurant circa 1959. The restaurant’s décor and menu will change dramatically every three months. “It’s built like a Metropolitan Opera stage set,” said the elder Mr. Stillman said.”Even if you’ve seen the opera before, people come back to see the new production.”

The summer iteration with rosé on the wine list and a cornucopia of fruits and vegetables on the menu, will disappear next month. “Summer is the most product-driven season,” Mr. Koketsu, said explaining that the bounty of Greenmarket goods need little coaxing on the plate. “Fall represents more of the process you go through, slow cooking and deeper flavors.”

Mr. Koketsu is effectively overseeing the cuisine at two restaurants now, but says he likes being busy. “When they first approached me with it I said, ‘Whoa!'” he said. “It seemed so out there, but now it’s just what we’re doing.”

Park Avenue Summer will close while AvroKo changes the interior from white and sunshine to dusky lighting, woods and leather. Park Avenue Autumn is scheduled to open for dinner on September 25th.

Michael Stillman will serve at the helm Fourth Wall Restaurants, a name chosen to evoke theater and the relationship between audience and performance. He spends most of his time in the restaurants dealing with the daily tasks involved in running a restaurant — from sourcing sugar cubes for the coffee to ordering seersucker summer chef jackets.

Alan Stillman’s title will be, simply, founder. “I’m not a retiring person, but I’d like to get out of the day-to-day,” he said. “I absolutely love it, 1,000% percent.”

Like father, like son.