A second teenage boy has been arrested in connection with the the alleged cyber attack on TalkTalk.
The 16-year-old was arrested in Feltham, west London, on Thursday by officers from Scotland Yard's cyber crime unit.
Officers carried out a search of the property, as well as an address in Liverpool.
The teen has now been released on bail until an unconfirmed date.
A Metropolitan Police Service spokesman said: "On Thursday, 29 October, detectives from the Metropolitan Police Cyber Crime Unit executed a search warrant at an address in Feltham.
"At the address, a 16-year-old boy was arrested on suspicion of Computer Misuse Act offences. He has now been bailed - we await confirmation of the bail date."
On Monday, a 15-year-old boy from County Antrim, Northern Ireland, was arrested by officers from the Police Service of Northern Ireland.
He has since been bailed until a date in November.