Buffett's Berkshire buys stakes in Kraft , GlaxoSmithKline

OMAHA -- There were several other changes in Berkshire's $68.8 billion portfolio of U.S. stocks. But the filings do not differentiate between investments Berkshire makes, investments any of its more than 60 subsidiaries make, or investments Buffett himself makes.

Berkshire spokeswoman Jackie Wilson said no one was available to comment Thursday, and the company does not generally comment on its stock investments more than it is legally required to.

The documents filed Thursday are the first ones to mention the Kraft investment, even though Berkshire started buying shares of that company in the second quarter 2007. Berkshire said in the filing that its authority to keep that investment confidential expired Thursday.

Buffett's company often asks the Securities and Exchange Commission for permission to not disclose information that could hurt its trading strategy because the market likes to follow what the company does.

Berkshire owned 311.4 million shares of Wells Fargo at the end of 2007. That's up from the 284.2 million shares of the bank Berkshire owned at the end of Sept. 30.

Berkshire increased its stake in the nation's largest specialty used-car retailer, Carmax, from nearly 14 million shares in September to 21 million shares at the end of December. Berkshire first invested in the Richmond, Va.-based company sometime in July, August or September.