Terms of the agreement include a one-year contract for the 2009 season, plus a club option for 2010. To clear a spot on the 40-man roster, the A's designated infielder Joe Dillon for assignment.
Giambi batted .247 with 32 home runs and 96 RBI in 145 games with New York last year, reaching the 30-homer plateau for the eighth time in his career. He tied for eighth in the American League in home runs and was second in at bats per homerun (14.3) and at bats per RBI (4.8). The left-handed hitter, who turns 38 on Thursday, led the AL in hit by pitches (22) and added 76 walks for a .373 on-base percentage. He made 112 starts at first base, his most as a Yankee.
Giambi spent seven seasons with New York, where he was a .260 hitter with 209 home runs and 604 RBI in 897 games. Previously, he batted .308 with 187 home runs and 675 RBI in 953 games in seven seasons with the A's. Giambi leaves New York ranked 10th on the Yankees all-time home run list and returns to the Athletics where he also ranks 10th in home runs, including sixth in Oakland history.
The 6-foot-3, 240-pound West Covina native is one of seven players in Major League history with 180 or more home runs
Giambi was originally drafted by the A's in the second round of the June, 1992 draft, and made his ML debut with Oakland in 1995. He was named American League MVP in 2000 after batting .333 with career highs in home runs (43), RBI (137) and walks (137), and then finished second in MVP balloting in 2001 when he set an Oakland record with a career high .342 batting average, while adding 38 home runs and 120 RBI. Giambi holds the Oakland career marks for batting average (.308) and on-base percentage (.412), and also ranks second on the Oakland career list in slugging (.545), fourth in doubles (228), sixth in RBI (675) and walks (586), tied for sixth in extra base hits (422), seventh in total bases (1851), 10th in runs (601) and tied for 10th in hits (1048).
Following his seven seasons with the A's, Giambi signed a seven-year contract with New York on Dec. 13, 2001. The deal also included a club option for 2009, which the Yankees declined to exercise on Nov. 4 of last year, making him a free agent. He slugged 41 home runs in each of his first two seasons, adding 122 RBI in 2002 and 107 in 2003, giving him five consecutive 30-home run seasons and six consecutive years with 100 RBI. Two stints on the disabled list limited him to just 80 games in 2004 but he came back to hit .271 with 31 home runs and 87 RBI in 2005 and was named AL Comeback Player of the Year.