Fitch has puts the UK on a negative watch - not a downgrade.
It will be a relief for the Treasury at the end of a big week that it is only a watch and not the loss of AAA status yet.
But it does mean that a downgrade from a second agency is now more likely by the end of April. This could be followed by a third downgrade, from Standard and Poor's.
More top news
Four in 10 European doctors are considering leaving the UK following Britain's vote to leave the EU, research suggests.
Eating 10 portions of fruit and veg every day could could significantly reduce the risk of heart disease and cancer, researchers say.
North Korea has blamed Malaysia for the death of Kim Jong-nam, the half-brother of North Korean leader Kim Jong-un.