Fenway Sports Group is expanding again, adding the NHL’s Pittsburgh Penguins to a portfolio that includes an English Premier League club, a NASCAR team and, of course, MLB’s Boston Red Sox.

An agreement that would give FSG, whose principal owner is billionaire John Henry, controlling interest in the Penguins was announced Monday by the NHL team, which did not disclose terms of the deal. The sale must be approved by the NHL’s Board of Governors and is expected to close before the end of the year, the team said. Sportico recently placed a value of $845 million on the Penguins, making them the NHL’s 15th-most-valuable team.

Besides the Red Sox, FSG owns Liverpool of the Premier League and Roush Fenway Racing in NASCAR, and it counts NBA star LeBron James as one of its part-owners. FSG also owns 80 percent of New England Sports Network and the Salem Red Sox, a minor league baseball team.

Mario Lemieux, the Penguins’ legendary former player, and Ron Burkle, an investor, were part of a group that rescued the team in 1999 when it was on the verge of bankruptcy, acquiring it for a reported $107 million. The group oversaw the construction of a new arena, and the team won the Stanley Cup three times after the arrival of Evgeni Malkin and Sidney Crosby. FSG said Lemieux and Burkle would remain part of the ownership group.

“The Pittsburgh Penguins are a premier National Hockey League franchise with a very strong organization, a terrific history and a vibrant, passionate fan base,” Tom Werner, FSG chairman and a co-founder, said in a statement. “We will work diligently to continue building on the remarkable Penguins’ tradition of championships and exciting play. We are particularly excited to welcome Mario Lemieux and Ron Burkle to FSG and have the utmost respect for all they have done to build the Penguins into the perennially successful franchise we know today.”

Lemieux said in a statement that he “will continue to be as active and engaged with the team as I always have been and look forward to continuing to build on our success with our incoming partners at FSG. They have an organizational philosophy that mirrors the approach that worked so well for Ron and me over the past 22 years.”

FSG received a roughly $750 million infusion from RedBird Capital Partners in March and joined RedBird, Nike and Epic Games in investing in SpringHill Company, the entertainment, marketing and content company founded by James and Maverick Carter. James and Carter joined FSG as partners, and RedBird became the third-largest FSG shareholder.

Fenway has looked to the NBA and NHL as it has pondered expanding its North American holdings. “We’re a huge admirer of the National Basketball Association and obviously the National Hockey League,” Sam Kennedy, the president and CEO of the Red Sox, said during a Sportico webinar in April (via ESPN). “It represents a natural place for Fenway Sports Group to look.”

Werner, the second-largest FSG shareholder, said during the MLB owners’ meetings that there were other possibilities, too: “We’re interested in expanding, and it doesn’t have to be that the only expansion is by acquiring a professional franchise.”

Retired MLB player Kevin Millar, who was with the Red Sox and Florida Marlins when Henry owned them, told the Pittsburgh Post-Gazette that he did not expect major changes and described an atmosphere unique to a conglomerate. “Obviously, it’s a business, and there’s a financial side to it,” he said recently, “but these guys are truly fans of the sport and the teams they’re owning. There’s a down-to-Earth-ness about them behind the scenes, they want to win, and you feel like there’s a family relationship with these guys.”

Millar added that Henry and Werner were a good fit for the Red Sox.

“You know they love the ownership side of it, but they do a great job of not crossing that line,” Millar said. “The owners that crowd you … they’re owners; they’re not GMs. And the ones who think they are, it never works out.”

Read more from The Post: