TalkTalk was hit by a hacking crisis last month as over 150,000 customers had their personal details exposed, in the third data breach the embattled telco firm has faced this year alone.
Four other people, three of them teenagers, have previously been arrested in connection with the ongoing investigation into the hack. The first arrest was made on 26 October, when a 15-year old from Northern Ireland was taken into custody. In the week that followed, a 16-year old from Feltham, a 20-year old from Staffordshire and a 16-year old from Norwich were also arrested. All four have since been bailed.
The 18-year old detained today was arrested in Llanelli, Wales, and taken into custody on suspicion of blackmail, the Metropolitan Police announced in a statement.
Read more: How does TalkTalk's fall compare?
TalkTalk's shares plummeted in the wake of the attack. Despite bouncing on surprisingly positive results from the firm, the price remains over 16 per cent down on what it was before the hack was made public.
Critics have called for chief executive Dido Harding to step down over the breach, but she has told City A.M. that she has no intention of leaving:
"If I was busy worrying about my job or my bonus right now I’d be doing my job extremely badly – and I’m not, I’m focused on doing what’s right for customers," she said.