Chicago ? The Chicago White Sox bought out Frank Thomas for $3.5 million Friday, making the top slugger in team history eligible for free agency.

The 37-year-old Thomas exercised a $10 million mutual option for next season Monday, giving the team five days to decide whether to exercise its half. The White Sox could try to re-sign the two-time AL MVP for less money.

“There should be no question about the respect this organization has for Frank and all that he has helped us accomplish, including a World Series championship,” general manager Ken Williams said in a statement. “He is the greatest hitter in White Sox history. At the same time, it is my responsibility to make the best decisions I can on behalf of the organization. Our plan now is to continue to speak with Frank and his representatives over the coming months as more information is known about his health.”

Thomas, who has missed most of the past two years because of foot and ankle problems, hit .219 with 12 homers in just 105 at-bats last season. He missed the first two months while recovering from surgery on his left ankle, then broke the ankle in July, ending his season.

A career .307 hitter with 448 homers and 1,465 RBIs, Thomas is the team’s leader in most offensive categories. He has spent his entire career with the White Sox and has said he wants to return.