US WiMAX operator Clearwire has reported its financial results for the fourth quarter and full-year 2011. Highlights included a record fourth-quarter revenue figure of USD361.9 million, up 107% year-on-year from USD175.2 million. Full-year revenues reached USD1.25 billion, up 134% year-on-year from USD535.1 million, while annual wholesale revenues rsoe 876% to USD493.7 million. At the end of December 2011 total subscribers reached 10.4 million, up by 140% from end-2010’s figure of 4.3 million. Clearwire also achieved positive quarterly adjusted EBITDA for the first time, posting USD22.5 million. It added that its average end-user 4G smartphone usage increased by 88% year-on-year in 4Q11.