Martin, 20, is an undrafted free agent that leads the Broncos in scoring while serving as club captain.
“Jon is a well-rounded player who brings a high skill set but also a tough, physical game.” Sharks GM Doug Wilson said in a release. “His game has really blossomed this season under Broncos General Manager and Head Coach Mark Lamb.
“As a result, he had a lot of suitors and we are thrilled that he has decided to join the Sharks organization.”
Helewka, also 20, was San Jose’s fourth-round pick at last year’s draft. He played well enough during the preseason to open this year with San Jose’s AHL affiliate, the Barracuda, but was returned to junior.
He’s since gone onto score 34 goals in 45 games, split between Spokane and Red Deer.