Shares in Sony fell 2% in Tokyo on Thursday morning after the company admitted a serious breach of its electronic security systems.
On Wednesday Sony warned that hackers have breached its online PlayStation network, compromising confidential information -including the names, addresses and possibly credit-card data of 77 million users.
PriceWaterhouseCooper's head of information security, William Beer, says data theft is becoming more frequent, but the industry hasn't seen an attack as large and extensive as the one on Sony.
"Hackers used to be the prime source of these types of attacks," Mr Beer says, "but now without a doubt we're seeing large groups of organised criminalss behind the attacks, using hackers sometimes as part of their operations."
