June 9
Signed C Rick Dempsey to a 3-year contract extension worth a total of $2,295,222.
Placed LF Rickey Henderson on the 15-day disabled list.
Purchased the contract of C Ernie Whitt from Triple A.
June 15
Traded 27-year-old starting pitcher Larry Christenson and 24-year-old minor league starting pitcher Francisco Velasco to the Montreal Expos, getting 34-year-old catcher Joe Ferguson in return.
Placed C Joe Ferguson on the 40-man roster.
Placed C Joe Ferguson on the active roster.