The team has reached an agreement with left-handed pitcher Mark Buehrle for four years and $58 million, sources told Stark.
The team also has an offer out to Rangers ace C.J. Wilson.
Hanley Ramirez's representative talked to the Marlins on Wednesday and asked for a restructured deal after the shortstop was asked to move to third base with the signing of Jose Reyes. The Marlins, upset with this, now are looking to trade Ramirez, the sources said.
Buehrle was down to three teams, a source told ESPN.com, before deciding on the Marlins. The Washington Nationals were also in the running, sources said. Other clubs believe the third was the Texas Rangers.
Wilson is being actively pursued by the Marlins and Los Angeles Angels. His agent, Bob Garber, also met Tuesday with his old team, Texas. The Nationals also maintain interest but are reluctant to guarantee either Wilson or Buehrle more than three years, sources said.
ESPN The Magazine's Buster Olney and ESPN.com's Jayson Stark contributed to this report.