Montero (lat) was transferred to the 60-day injured list Wednesday, Chandler Rome of the Houston Chronicle reports.
Montero has been on the injured list since Aug. 10 due to a lat strain, so his move to the 60-day IL means that he won't have enough time to return during the regular season. The Astros haven't yet indicated whether Wednesday's transaction was prompted by a setback in the right-hander's recovery, and it's not clear whether he could be available for a potential postseason run.