Few companies--including Home Depot (HD) or Bank of America (BAC)--are as exposed to a downturn in U.S. housing as USG Corporation. The company makes virtually all of its operating profit (70%+ in 2006) from drywall sales, which are used in new home and office construction. The company may have stellar operating improvements and Warren Buffett as the major shareholder, but the Oracle of Omaha got in at $17 per share in 2000. Around $40 per share these days, USG's stock has not priced in the entire effect of the subprime lending crisis yet. Wait for the price to go lower if you have an appetite for gypsum, the main component of drywall.