Supergroup has parted company with chief operating officer Susanne Given, with the shock announcement sending the shares lower on Thursday afternoon.Given has departed with immediate effect "to explore other opportunities", less than four months since new chief executive Euan Sutherland took the reins.The street fashion and retail group, which is known for its SuperDry brand, said the "substantial" strengthening of the management team meant that her responsibilities could now be absorbed by the executive team with the heads of UK retail, IT and logistics reporting directly to Sutherland.Given joined the business in April 2012 and has been responsible for the UK Retail division together with central support functions.Independent retail analyst Nick Bubb said: "Shock news today that the excellent Susanne Given, who has done a great job in getting Supergroup's operating and distribution systems back into shape in the last thee years, is leaving with immediate effect."He added: "It looks as if she has fallen victim to internal politics, in the wake of Euan Sutherland's recent arrival as CEO."Chairman Peter Bamford said: "Susanne played a crucial role in leading key investment programmes which have upgraded the infrastructure and processes of our business and were recently tested to the full over the peak Christmas trading period. We wish her every success in her future career."After a tortuous 2014 in which its shares slumped almost 50%, a January trading update indicated the FTSE 250 group had ended the calendar year strongly, with a Christmas trading period that underpinned its full year profit guidance.Like-for-like sales grew by 12.4% in the 11 weeks to 10 January, with total retail sales increased by 17.8%.Supergroup enjoyed record trading period from its e-commerce platform, which it attributed to customers having "growing confidence" in the group's delivery promise.