| Trans Num | Date | Details |
| 1921.11 | 2023-05-26 | Cooperstown Giants trade Johnny Mostil to the Mannheim Steamrollers for Bobby Veach. |
| 1920.4 | 2023-03-24 | Cooperstown Giants trade COO 1920 #1 and COO 1920 #2 to the Holyoke Purple Knights for Johnny Mostil and Mickey O'Neil. |
| 1920.1 | 2023-03-18 | Holyoke Purple Knights trade Elmer Myers, Joe Gedeon, and HOL 1920 #2 to the Mannheim Steamrollers for Johnny Mostil and Larry Doyle. |