Shares in Advanced Micro Devices fell to a 16-year low yesterday as $1bn in second-quarter charges highlighted its struggle to slim operations and return to profitability.

AMD announced the second writedown from its 2006 acquisition of the Canadian graphics chipmaker, ATI. It said it was taking an impairment charge of $880m, following a charge of about $1.5bn last year. It paid $5.4bn for ATI.