The cyber attack on TalkTalk was "smaller" than it was first thought, the telecoms firm has said.
TalkTalk's website was breached on Wednesday, and it was thought that millions of customers' information, including bank account details, were stolen. But TalkTalk chief executive Dido Harding said only partial financial information would have been stolen - and not enough to withdraw funds.
The company, which was also hit with a ransom demand following the cyber attack, said it would "pause" its marketing activities while it deals with the attack, including its high-profile sponsorship advertising of X Factor.
Its shares fell 4.2% Monday morning, following a 4.4% drop on Friday. Meanwhile, its biggest rivals BT and Sky have seen their shares rise 11% and 23% respectively.
Some customers have expressed anger and frustration at TalkTalk's response to the cyber attack. TalkTalk said it would contact all four million of its customers, but some are yet to receive any word from the company.
TalkTalk has also received criticism over its refusal to allow customers to cancel their contracts for free. But it said that it would look at it on a case-by-case basis. Speaking to the BBC on Friday, Ms Harding said: "Waiving standard terms and conditions is not something sensible I can do today."