The FCA was hit by a widespread IT outage on Friday which affected its regulatory reporting system Gabriel.
In a statement, the regulator says most of its systems are now operating again following a “physical hardware incident” at a supplier’s data centre.”
The FCA says: “We put in place our recovery arrangements and they have operated as planned.”
The Financial Times reports Fujitsu was the supplier that caused the outage, with other customers alongside the FCA affected.
It comes less than a week after a senior FCA official warned of a spike in the number of cyber attacks on financial services firms.
The FCA says there was no hack or denial of service attack on its systems.