What happened: Minor leaguers outside 40-man rosters can still be traded afterward. Players must join an organization by Aug. 31 to be eligible for its postseason roster.

Why it matters: The single deadline leaves contenders one final window to reinforce their rosters for the stretch run. MLB eliminated its separate August waiver-trade period in 2019.

What to watch: Watch for completed deals and corresponding roster moves before Monday's cutoff.