Shares in the two companies accused of overcharging the Ministry of Justice for its electronic tagging contracts had fallen at the end of trading today.
Shares in Serco fell about 8% while those in G4S were almost 6% lower.
More top news
Early cloud and rain will slowly clear away from southeast England and East Anglia.
A Cornish fish restaurant has been named the best in the UK - knocking Cumbria's L'Enclume into second place after five years at the top.
There "will not be a war again on the Korean Peninsula", South Korea's President Moon Jae-in has said.