The Hawks received Ivan Vishnevskiy and a second-round pick in next year's draft.
"I kind of knew it was coming," Ladd said on "The Afternoon Saloon" on ESPN 1000. "Obviously, you want to stay where you just won the Stanley Cup, but at the same time, I'm going to a team with a lot of familiar faces."
"It became apparent it wasn't the right mix as far as salary and our situation here," Hawks general manager Stan Bowman said of the Ladd deal. "We're going to see what we can add to the mix now. I think we alleviated the [cap] situation we were in."
Ladd is unsigned as a restricted free agent and is arbitration eligible.
ESPN.com's Pierre LeBrun contributed information to this story.