OMAHA, Neb. (AP) — Billionaire Warren Buffett donated stock in his company worth $41.6 million to eight unnamed charities during the second half of 2011.

Buffett revealed the donations Wednesday in a year-end update on his Berkshire Hathaway Inc. stock holdings.

Buffett gave away 521,292 Class B shares of Berkshire stock between July and the end of December. These gifts are in addition to Buffett's annual gifts to the Bill & Melinda Gates Foundation and the four Buffett family foundations that are slated to eventually receive most of Buffett's fortune.

The new stock donations included one sizeable gift of 394,737 shares worth roughly $31.5 million.

Buffett has said he plans to eventually donate all of his 350,000 Class A and 26.2 million Class B shares of Berkshire stock worth about $44 billion to charities.