Martinsen signed a contract with EV Zug of the Swiss NLA League on Tuesday, Seth Rorabaugh of Tribune-Review Sports reports.
Martinsen was placed on unconditional waivers by the Penguins on Friday, Elliotte Friedman of Sportsnet reports.
Martinsen was acquired by Pittsburgh from Anaheim on Friday, along with a 2021 seventh-round pick, in a swap for Erik Gudbranson.
Martinsen signed a one-year, two-way contract with the Ducks on Friday.
The Blackhawks placed Martinsen on waivers Friday, Scott Powers of The Athletic reports.
Martinsen (back) will play Saturday versus the Blue Jackets, Chris Wescott of the Blackhawks' official site reports.
Martinsen inked a one-year contract extension with Chicago on Thursday.
Martinsen was reassigned to AHL Rockford on Sunday.
The Blackhawks recalled Martinsen from AHL Rockford on Tuesday.
The Canadiens traded Martinsen to the Blackhawks in exchange for Kyle Baun on Wednesday.