Additions
| from | Name | Pos | Team | Team | ||
|---|---|---|---|---|---|---|
| 07/2013 |  | Jon Ander | GK |  | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Remiro | GK | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | De Eguino | DF | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Elgezabal | DF | |||
| 07/2013 | | Imanol Corral | DF | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Jon Agirrezabala | DF | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Urtzi Iriondo | DF | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Yeray | DF | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Gorka Iturraspe | MF | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Jon Etxaburu | MF | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Jurgi | MF | |||
| 07/2013 |  | Yanis Rahmani | MF | | Athletic Club U19 | Bilbao U19 |
| 07/2013 |  | Iñaki Williams | FW | | Athletic Club U19 | Bilbao U19 |
| 07/2013 | | Villalibre | FW |
Departures
| from | Name | Pos | Team | Team | ||
|---|---|---|---|---|---|---|
| 07/2013 | | Urtzi | GK |  | Athletic Club B | Bilbao B |
| 07/2013 | | Eneko Zabaleta | DF |  | Arenas de Getxo | Arenas de Getxo |
| 07/2013 | | Markel Etxeberria | DF | | Athletic Club B | Bilbao B |
| 07/2013 | | Mikel | DF | | Athletic Club B | Bilbao B |
| 07/2013 | | Iker Undabarrena | MF | | Athletic Club B | Bilbao B |
| 07/2013 | | Iñigo Lekue | MF | | Athletic Club B | Bilbao B |
| 07/2013 | | Salinas | MF |  | SD Amorebieta | SD Amorebieta |
| 07/2013 | | Unai López | MF | | Athletic Club B | Bilbao B |
| 07/2013 | | Sabin | FW | | Athletic Club B | Bilbao B |