Although the papers usually refer to it as a transfer ban. The ban is actually on registering new players l believe. Quite a few transfers seem to be before you can actually register the player nowadays.Surely a ban is a ban.
Atletico should not be able to buy whilst a ban is in place. It appears not though.
Buy, loan back then register when ban ends. A farce.
If ban ends December, then when window opens in January they can buy.