The A's acquired infielder Jed Lowrie and right-hander Fernando Rodriguez from the Houston Astros for first baseman Chris Carter and two minor leaguers on Monday.
Right-hander Brad Peacock and catcher Max Stassi also went to Houston in the deal between franchises that will be playing in the same division for the first time following the Astros' move from the NL Central to the AL West starting this year.
Lowrie batted .244 with 16 homers and 42 RBIs in 97 games with Houston, missing two months with ankle and thumb injuries. Despite the limited playing time, Lowrie tied for the fourth most homers among all shortstops last year.
Oakland general manager Billy Beane said he has had interest in Lowrie for years and was glad to be able to get the chance to add him to the roster.
"He always had good power for a guy in the middle of the infield," Beane said. "It's just hard to find that kind of power from a guy who can play the middle of the infield and doing it as a switch-hitter."
Lowrie played exclusively at shortstop last season but previously played first, second and third base as well during his four years with the Boston Red Sox. The A's had previously signed Japanese shortstop Hiroyuki Nakajima to a $6.5 million, two-year contract.
Nakajima starts off as the shortstop but Beane said there will be plenty of chances for Lowrie to play all over the infield.
"I feel most comfortable at shortstop," Lowrie said. "But I've played some second base in my career as well. I'm certainly more comfortable up the middle than anywhere else on the diamond. But I've had some experience at third base."
Lowrie, who played his college ball at nearby Stanford, agreed to a $2.4 million salary to avoid arbitration. The Astros are likely to have the lowest payroll in the majors in 2013.
The move sends Lowrie from a rebuilding franchise that had a major league-worst 107 losses last season to a young club coming off a surprising division title in 2012 and one with high hopes for this season.