The team can not sign players until next January
Atletico Madrid's transfer ban has been upheld by the Court of Arbitration for Sport (CAS).
The Spanish side were handed a transfer ban for the length of two transfer windows, last year. The ban was appealed, allowing the team to sign players last summer.
Atletico were banned as a result of issues signing minor players. The ban began in January's transfer window.
In a statement released by CAS on Thursday morning, the revealed the fine was reduced by 900,000 Swiss Francs to 550,000 (approx €460,000).
"The Panel found that not all of the alleged violations of the FIFA regulations concerning the registration of minor players could be upheld, which justified a reduction of the fine... but not of the transfer ban imposed on the club by FIFA."
Atletico Madrid reacted to the news by stating they had planned for both scenarios, and are already preparing to enter the transfer market in January.
"The club has the commitment of the players and coaching staff to continue competing at the same level next season, despite this decision that is evidently detrimental to us. Together, team, club and supporters, we will continue to fight for our goals."
News of the CAS decision means that Atletico are unlikely to sell any of their major players this summer, including France international Antoine Griezmann.