The shocking blockbuster deal that sent P.K. Subban to the Nashville Predators for Shea Weber on Wednesday was arguably the worst trade in the history of the Montreal Canadiens, and unquestionably one of the biggest.

That's pretty significant, considering the Canadiens have been in the NHL since 1917.

Over that near-century, more than a handful of deals have reshaped the franchise and altered the direction of the club for years afterward.

Here are the five biggest trades in the history of the Canadiens.

Patrick Roy to the Avalanche

If there's one deal that stirred as much controversy as Wednesday's one-for-one swap, it was Patrick Roy's exit in 1995.

The three-time Vezina Trophy winner won two Stanley Cup championships with the Canadiens before his infamous falling-out with head coach Mario Tremblay during an embarrassing 11-1 loss to the Detroit Red Wings.

Four days later, the star goaltender was shipped to the Colorado Avalanche along with captain Mike Keane for forwards Andrei Kovalenko and Martin Rucinsky, as well as netminder Jocelyn Thibault.

Roy won the Cup with the Avalanche in 1996 and cemented his Hall of Fame legacy. The Canadiens haven't returned to the final since he was dealt.

Subban for Weber

There's no way to sugarcoat it: The Canadiens got significantly worse by dealing away a 27-year-old franchise defenseman in the prime of his career for a declining 31-year-old with an atrocious contract.

The trade immediately outraged many Canadiens fans, some of whom swore off the team after the departure of the dynamic superstar, who made the largest charitable donation ever by a Canadian athlete last fall.

What made it most confounding is that Canadiens management gave no specific reason for making the deal, and it's a trade the club and its fan base won't soon forget.

Sealing California's fate

Guy Lafleur could have been a California Golden Seal if not for a major trade.

The Canadiens acquired the first overall pick in the 1971 draft from California along with Francois Lacombe for 1970 first-rounder Chris Oddleifson and veteran forward Ernie Hicke.

Montreal selected Lafleur with the top pick in '71, and it was a brilliant choice.

He won the Cup five times with Montreal, finishing his Hall of Fame career as the franchise's all-time assists and points leader. He ranks second in Canadiens history in goals (518) behind Maurice "Rocket" Richard (544).

Five years after the trade, the Golden Seals relocated to Cleveland and became the Barons before merging with the Minnesota North Stars in 1978.

Toe Blake goes across town

After playing eight games for the Montreal Maroons and winning the Stanley Cup in 1935, left winger Hector "Toe" Blake was traded to the Canadiens for goaltender Lorne Chabot in 1936.

That turned out to be a steal for the Habs. Blake won the Hart Trophy as the NHL's most valuable player in 1939, authored six 20-goal seasons, and won two more championships with the Canadiens in 1944 and 1946.

Blake's biggest contributions with the Canadiens came behind the bench. After eight years coaching the club's affiliates, he was named head coach of the NHL club in 1955.

He won the Stanley Cup in each of his first five seasons in the role, and guided the team to eight championships between 1956 and 1968.

Canadiens land 'The Big M'

Frank Mahovlich was a 16-year NHL veteran at the time of his trade from the Detroit Red Wings, but he turned out to be a major addition for the Canadiens.

Mahovlich was traded along with defenseman Bart Crashley for center Garry Monahan and minor-league blue-liner Doug Piper. Mahovlich played his final four NHL seasons with the Canadiens, notching a 43-goal season and three campaigns with at least 30. He won two championships with Montreal, giving him six in his career.

Monahan, Montreal's first overall pick in 1963, was the only other player to suit up for an NHL team after the deal. He collected seven points in 51 games with the Red Wings before moving on to the Los Angeles Kings, Vancouver Canucks, and Toronto Maple Leafs.

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