Stockholder Right Plan

12 Months Ended

Dec. 31, 2011

Stockholder Rights Plan [Abstract]

Stockholder Rights Plan

15. Stockholder Rights Plan

On December 21, 2006, our Board of Directors approved the adoption of a stockholder rights plan. The plan was amended on December 5, 2008. Under the rights plan, if any person or group acquires beneficial ownership of 15% or more of our then-outstanding voting stock, stockholders other than the 15% triggering stockholder will have the right to purchase additional shares of our common stock at half the market price, thereby diluting the triggering stockholder. During a seven-year standstill period that expires in August 2013, Berkshire Hathaway Inc. (and certain of its affiliates) will not trigger the rights so long as Berkshire Hathaway complies with the terms of a shareholder’s agreement we entered into with Berkshire Hathaway and, following that seven-year standstill period, the term “Acquiring Person” will not include Berkshire Hathaway (and certain of its affiliates) unless Berkshire Hathaway and its affiliates acquire beneficial ownership of more than 50% of our voting stock on a fully diluted basis. Among other things, the shareholder’s agreement limits during the standstill period Berkshire Hathaway’s acquisitions of beneficial ownership of our voting stock to 40% of our voting stock on a fully diluted basis, except in limited circumstances, and the manner in which it may seek to effect an acquisition or other extraordinary transaction involving USG.

The rights issued pursuant to the stockholder rights plan will expire on January 2, 2017. However, our Board of Directors has the power to accelerate or extend the expiration date of the rights. In addition, a Board committee composed solely of independent directors will review the rights plan at least once every three years to determine whether to modify the plan in light of all relevant factors. The first of those reviews was conducted in November 2009, and no modification of the plan was adopted. The next review is required by the end of 2012.