The person spoke to The Associated Press on condition of anonymity Saturday because the transactions had not been announced. Each player went on unconditional waivers at noon with the purpose of his club buying out his contract.
Minnesota saves more than $2.4 million against the $79.5 million salary cap next season by buying out the final year of Ennis' contract. The 28-year-old, who was due to make $3.65 million and count $4.6 million on the salary cap, had 22 points in 73 games with the Wild after being acquired from Buffalo a year ago.
The Canadiens took on Mason's salary in a trade with Winnipeg that got them young Finnish forward Joel Armia. Montreal will have a cap hit of just under $1.4 million over the next two seasons for the 30-year-old goaltender, who becomes an unrestricted free agent.