HTC's executive exodus has continued following the departure of Chief Operating Officer (COO) Matthew Costello. Bloomberg reports that Costello leaves his position after less than three years at the company, and will be replaced by Fred Liu, who will expand his role as president of engineering and operations. Costello becomes the third HTC executive to leave the company in as many weeks, following former Chief Product Officer Kouji Kodera and HTC Asia CEO Lennard Hoornik.

Earlier today, the company posted its highest monthly revenue ($967 million) in 11 months following the launch of its flagship HTC One smartphone in April, but was still down 3.3% on last year. In an attempt to improve its manufacturing processes, HTC told Bloomberg it will form a new quality assurance division to enhance product reliability, also assigning a new team to look after product lifecycle matters. Last month we revealed the growing disarray at its North American headquarters, with one source describing HTC as a company in "utter freefall." HTC CEO Peter Chou has promised to step down if the One isn't a retail success, but the company has reportedly sold "around five million" units since its release and will soon sell a Nexus model running stock Android on June 26th. HTC says it has weathered early supply issues, but there's little evidence to suggest the company will be able to match Apple or Samsung's smartphone sales any time soon.