The Astros signed Walter (shoulder) to a minor-league contract Thursday.
The Red Sox released Walter (shoulder) on Friday, Ian Browne of MLB.com reports.
The Red Sox designated Walter (shoulder) for assignment Tuesday, Gabrielle Starr of the Boston Herald reports.
Triple-A Worcester transferred Walter (shoulder) from its 7-day injured list to the 60-day IL on Wednesday.
Walter will begin the season on the injured list due to a strained left shoulder, Chris Cotillo of The Springfield Republican reports.
The Red Sox optioned Walter to Triple-A Worcester on Wednesday, Pete Abraham of The Boston Globe reports.
Walter struck out two over two hitless and scoreless innings in Tuesday's spring game against St. Louis.
Walter was optioned Friday to Triple-A Worcester, Chris Cotillo of The Springfield Republican reports.
Boston recalled Walter from Triple-A Worcester on Wednesday, Chris Cotillo of The Springfield Republican reports.
Walter was optioned to Triple-A Worcester on Saturday.