The Athletics selected Stefanic's contract from Triple-A Las Vegas on Friday.
Stefanic has spent the majority of the 2026 season with Las Vegas, where he's slashed .296/.405/.414 with six homers, 59 RBI, 59 runs scored, nine stolen bases and a 59:43 BB:K across 453 plate appearances in the Triple-A club's hitter-friendly confines. He'll serve as infield depth with the big club.