Frattin, 25, was expected to play a vital role on Los Angeles' second line with Mike Richards and Jeff Carter after being acquired from Toronto in the summer with goalie Ben Scrivens in exchange for netminder Jonathan Bernier, but he has struggled this season and has mainly seen duty on the fourth line.
In 22 games with the Kings so far this season, Frattin has collected two goals and four assists for six points, and has a team-worst minus-7 rating.
Frattin is making $900,000 this season, though his salary cap hit is $437,500, as the other half of his $870,000 cap hit is being paid by the Maple Leafs.
The Kings are looking to shed some salary, but moving Frattin might not be their first choice. It's believed forward Kyle Clifford and defenseman Alec Martinez are available for trade.
The Sun reports the Senators are looking for a winger to play alongside Jason Spezza.