LONDON (Reuters) -The explosion in the value of artificial intelligence stocks poses risks to global ​markets for which there is “no playbook”, the CEO ‌of Deutsche Bank’s 1.1 trillion euro ($1.3 trillion) money manager DWS told Reuters,‌ amid growing concerns that the sector is in a bubble. The AI stocks frenzy has drawn comparisons with the 1990s dotcom boom and bust, but DWS’s Stefan Hoops said today’s rally was different as it was being driven by everyday retail investors ⁠– not institutions –‌ and they had yet to be tested. The Frankfurt-based asset manager is examining whether such a boom could unravel at a faster ‍pace, Hoops said in an interview, adding that the many retail investors sitting on big gains on stocks such as Nvidia could be quick to sell if sentiment soured.