JJ Peterka was traded to the Boston Bruins by the Utah Mammoth on Friday.
The Mammoth received the No. 23 pick in the 2026 NHL Draft and a conditional first-round pick in the 2028 NHL Draft. Boston had received the 2028 first-round pick from the Florida Panthers in the deal for forward Brad Marchand on March 7, 2025.
Utah then traded the No. 23 pick to the Detroit Red Wings later in the evening for goaltender Sebastian Cossa.
“We’ve got some really good, younger players coming and I felt like we had to create a little bit of room for them in some areas and some offensive situations,” Mammoth general manager Bill Armstrong said. “And I think JJ was a great player for us, obviously, to get two first rounders for him. It’s a great value. One first rounder allowed us to go get one of the goaltenders we’ve been hunting for the last few years, and then I think with the other pick, it allows us to have some ability to make some bigger deals down the stretch with another first rounder in the bank. And so I think it gives us a lot of flexibility. It gives our younger guys an opportunity and gives us an opportunity to put a young kid in net that we feel he’s got a chance to really take a step and maybe be a goaltender of the future for us.”
Peterka had 47 points (25 goals, 22 assists) in 82 games this season, his first with the Mammoth after being acquired in a trade with the Buffalo Sabres on June 26, 2025. He did not have a point in six Stanley Cup Playoff games.
The 24-year-old forward has four seasons remaining on a five-year, $38.5 million contract ($7.7 million average annual value) he signed on the day he was acquired by Utah.
Selected by Buffalo in the second round (No. 34) of the 2020 NHL Draft, Peterka has 197 points (92 goals, 105 assists) in 320 regular-season games for the Sabres and Mammoth.
Cossa went 26-8-4 with a 2.33 goals-against average, .915 save percentage and five shutouts in 39 games for Grand Rapids of the American Hockey League this season.
The 23-year-old, who was selected by Detroit in the first round (No. 15) of the 2021 NHL Draft, can become a restricted free agent on July 1.
“You look at his work in the [AHL] over the last few years, he’s at the point where he’s accumulated enough games in the [AHL], and his age is absolutely perfect. And now he’s going to have that opportunity to take that next step,” Armstrong said. “I feel like he was a goaltender that we moved toward, and he has a chance to really step in here and be a huge piece of our club next year.”
The Mammoth (43-33-6) qualified for the playoffs in just their second season as a franchise this season. As the first wild card from the Western Conference, they were eliminated by the Vegas Golden Knights in six games in the first round.
The Bruins (45-27-10) finished as the first wild card from the Eastern Conference this season and were eliminated by the Sabres in six games in the first round.
