(ShareCast News) - The 15-year old boy arrested over an alleged cyber attack on TalkTalk has been released on bail, police said.Police said the boy from Country Antrim in Northern Ireland, who was arrested on Monday on suspicion of offences under the Computer Misuse Act, was released on bail on Tuesday morning.A spokesman for the Police Service of Northern Ireland said: "The investigation being conducted by the Metropolitan Police Cyber Crime Unit, Police Service of Northern Ireland and National Crime Agency is continuing."TalkTalk was contacted by criminals last week asking for a ransom, but other groups have also claimed responsibility in recent days.TalkTalk shares tumbled in the previous session as investors worried about the impact of the hack, but by 1310 GMT on Tuesday, they were bouncing back, up 15% to 258.80p.Market participants said the arrest, along with the company's refusal to give in to customer demands to waive contract cancellation fees have alleviated fears somewhat.TalkTalk announced last Friday that a criminal investigation had been launched by the Metropolitan Policy cyber crime unit following a "significant and sustained" cyber attack on the company's website.On Saturday, the company said the amount of financial information that may have been accessed was likely to have been materially lower than initially believed and would on its own not enable a criminal to take money from a customer's account.