Merida failed to agree on a new contract with Arsenal and will be able to join Atletico on a free transfer.
Merida has signed a five-year contract with the Spanish giants.
The 20-year-old was highly-rated by Arsenal manager Arsene Wenger.
Merida failed to agree on a new contract with Arsenal and will be able to join Atletico on a free transfer.
Merida has signed a five-year contract with the Spanish giants.
The 20-year-old was highly-rated by Arsenal manager Arsene Wenger.
