Comcast (NSDQ: CMCSA) announced in its fourth-quarter earnings release that it would take an impairment charge of $600 million on its investment in the struggling wireless broadband internet provider Clearwire (NSDQ: CLWR). The writedown amounts to nearly half of its original $1.5 billion investment in the company in early 2008.

SEE ALSO: Intel Writes $950 Million Off Clearwire Investment, Time Warner $350 Million

Comcast isn’t the only original investor writing down its Clearwire’s stake. In January 2009 Intel (NSDQ: INTC) wrote down $950 million of its investment, Time Warner (NYSE: TWX) wrote down $350 million, and Google (NSDQ: GOOG) wrote down $355 million. With Comcast’s writedown today, total writedowns made in 2009 on Clearwire add up to a sizable $2.3 billion—equal to about half of the company’s approximately $4.1 billion market cap when it went public in March 2007. Clearwire uses wireless technology and spectrum given up by ATT following its merger with BellSouth to provide internet services to markets in the U.S., Europe and Mexico.