Spanish giants Real Madrid and Atletico Madrid have been banned from registering players for the next two transfer windows.
They have been punished by world governing body Fifa for breaching rules over the transfer of minors – and Atletico say they will appeal.
The ban does not cover the current January transfer window.
Atletico were fined 900,000 Swiss francs (£622,000), while Real were told to pay 360,000 (£249,000).
“Our club is not in agreement with the sanction from international football’s governing body and will study all the documentation we’ve received to present an appeal against the sanction,” said an Atletico statement.
Real Madrid have yet to comment.
Barcelona were given the same penalty in April 2014 for also breaching rules on the transfer of under-18 players.
Their ban, which ended this month, did not stop the La Liga side from signing players.
They bought Arda Turan and Aleix Vidal in the summer of 2015, though both players were prevented from playing until the current window opened.
The next two transfer windows are July/August 2016 and January 2017.