The development firm HYM Investment Group is expected on Friday to close on its purchase of the all-but-shuttered horse track for $155 million and will begin turning the 161-acre site into East Boston’s answer to other mega-developments such as Assembly Row and Boston Landing — only much bigger.

The quiet stables, little-used track, and empty parking lots at Suffolk Downs are slated to become a huge hub of housing, shopping, and park space as new owners close out eight decades of horse racing.


It would be perhaps the largest single development in urban Boston, and will probably cost in the billions to fully build out over a decade or more, said HYM’s managing director, Tom O’Brien. He has few specifics just yet, but points to the successful Assembly Row complex in Somerville as an example of the type of project he has in mind for Suffolk Downs.

“It’s a rare, almost nonexistent opportunity to do something really special on a very big site,” O’Brien said. “It’s the kind of place that has been underappreciated for a long time.”

HYM and its investment partner are buying the track from Sterling Suffolk Racecourse, which put Suffolk Downs on the block after it failed to win a casino license. Horse racing has been dwindling at Suffolk Downs for years, down to just six live races this season. The simulcast operation and a few races are likely to continue at Suffolk for another year. Sterling Suffolk has told gaming regulators that it plans to remain in the simulcasting business, though it’s not yet clear where.

Sterling Suffolk principal Joe O’Donnell knew Suffolk Downs would be redeveloped after the Massachusetts Gaming Commission awarded the casino license for Greater Boston to Wynn Resorts in 2014. Suffolks Downs has been hosting horse races for about eight decades, but it has lost money for years. Without a casino to offset those losses, it became time to sell.


“We talked to pretty much everybody who would be interested,” O’Donnell said. “We did it in the way I like to do most things: low-key and under the radar.”

In February, O’Donnell’s group signed a sale agreement with O’Brien’s. The two businessmen are longtime friends, and O’Brien, a former director of the Boston Redevelopment Authority, has been involved in other big mixed-use projects in the area, such as Boston Landing in Brighton and NorthPoint in East Cambridge.

“There’s no question it’s the right thing to do for the property,” O’Donnell said of selling to O’Brien. “He’s loaded with integrity.”

O’Brien’s plan for Suffolk Downs would follow a familiar playbook for developers in the Boston area: Find a big, tired property located near public transit and turn it into a modern, mixed-use hub that triggers additional redevelopment nearby. The racetrack is next to two MBTA Blue Line stations.

“You just have tremendous potential,” said Brendan Carroll, director of intelligence at the real estate firm Perry Brokerage Associates. “It’s the sort of thing that could really put a different face on that whole part of the region.”

Suffolk Downs is one of three huge parcels in East Boston and Revere that are changing hands.

In April, the 50-acre Necco candy factory site on Route 60 in Revere sold for almost $55 million, and its owners said they may redevelop it in the next few years.


O’Donnell and his partners are also selling the shuttered Wonderland dog track, across the railroad tracks from the Necco plant, and expect to demolish the building this summer.

“Things are breaking Revere’s way,” Revere Mayor Brian Arrigo said.

With business at the tracks winding down, Revere has struggled to attract major employers to replace them. Necco still has more than 600 workers, according to city figures, but Revere’s second- and third-biggest private employers are a Stop & Shop supermarket and a movie theater.

That has Arrigo lobbying to have more office space built at the Suffolk Downs site, about one-third of which is in Revere. He envisions something akin to the big Partners HealthCare facility at Assembly Row.

“Those days of the tracks, both Wonderland and Suffolk Downs, being the economy of the city are gone,” Arrigo said. “We have the next opportunity to really make sure we have quality jobs for folks in the city of Revere.”

O’Brien, who declined to name HYM’s investment partner, said plans for Suffolk Downs are still preliminary. But he envisions new streets with restaurants and stores at ground level, and housing above. Office space would probably follow later, he said, once the neighborhood has become established.

At least one-quarter of the old Suffolk Downs site would be set aside for open space and wetlands, and O’Brien expects to discuss upgrades to Route 1A and possibly the two Blue Line stops with state officials.


O’Brien expects to continue meeting with local elected officials and neighborhood groups and hopes to file formal plans with Boston later this year and start construction in 2018.

The Boston Planning & Development Agency recently singled out Suffolk Downs in its new Imagine Boston 2030 plan as one of six pockets of the city with potential for large-scale development. The plan envisions a “new, mixed-income neighborhood” that’s designed to “strengthen the area’s resilience to flooding” — a nod to climate-change concerns in a low-lying neighborhood between the Chelsea River and Belle Isle Marsh.

“We look forward to working with the new owner, the City of Revere, and the community to realize the tremendous potential of this site to the City of Boston,” said BPDA director Brian Golden.

Neighbors are hopeful, too.

Nicolas Joly bought a house in Orient Heights four years ago, just up the hill from Suffolk Downs. He likes both the diversity of East Boston and his quiet little slice of it, but wouldn’t mind having stores and restaurants within an easy walk, or more open space. Traffic is a concern, Joly said, but what little he’s heard so far about the Suffolk Downs plan, he likes.

“I’m excited for it,” he said. “I think the pros will outweigh the cons.”

Traffic also concerns Joanne McKenna, a Revere city councilor who lives near Suffolk Downs. But the benefits of having an Assembly Row-style mixed-use development there, she said, are likely to outweigh any downsides.


“People are more on board with that than a casino,” McKenna said. “I just think it’s going to be great for Revere.”

Tim Logan can be reached at tim.logan@globe.com. Follow him on Twitter @bytimlogan.