OMAHA, Neb._Billionaire Warren Buffett's company revealed Friday that it had bought a new stake in medical supply company Becton, Dickinson & Co. and boosted its holdings in Johnson & Johnson during the second quarter.

Berkshire Hathaway Inc. disclosed those investments and several other changes to its roughly $49 billion U.S. stock portfolio in documents filed with the Securities and Exchange Commission. The filing offers a snapshot of the Omaha-based company's holdings as of June 30.

Berkshire reduced its holdings in CarMax Inc., ConocoPhillips, Eaton Corp., Home Depot Inc., and health insurers UnitedHealth Group Inc. and WellPoint Inc.

But the filing also says Berkshire has received permission from the SEC to omit some information to protect its trading strategy, so the document offers an incomplete picture of the company's investments.

Berkshire regularly asks the Securities and Exchange Commission for the ability not to immediately disclose its holdings when it is making significant changes in an investment. Berkshire says the information could hurt its trading strategy because the market likes to follow what the "Oracle of Omaha's" company does.

Friday's filing is the first to mention a stake in Franklin Lakes, N.J.-based Becton Dickinson. At the end of June, Berkshire held 1.2 million shares of the maker of medical devices and lab equipment.

Berkshire officials do not typically comment on the company's investment decisions beyond what is legally required, and they did not immediately respond to an interview request Friday.

Berkshire appears to be rebuilding its stake in Johnson & Johnson by buying 4.4 million shares in the second quarter after buying 3.9 million in the first quarter. Last fall, Buffett sold off 33.1 million shares of the New Brunswick, N.J.-based drug and medical products maker to free up cash for other investments.

In May, Buffett told shareholders he would have liked to keep all of the 61.8 million J&J shares that Berkshire held a year ago, but he decided at the time that the cash was needed to preserve a comfortable reserve while investing $8 billion in Goldman Sachs Group Inc. and General Electric Co.

Between March 31 and June 30, Berkshire cut its holdings in several stocks, including:

_ Selling 6.7 million shares of ConocoPhillips stock, giving Berkshire 64.5 million shares in the oil company.

_ Selling 3 million shares of used-car dealer CarMax Inc., leaving Berkshire with 9 million shares.

_ Selling 1.2 million shares of industrial equipment maker Eaton Corp. to leave 2 million shares in Berkshire's portfolio.

_ Selling 1.2 million shares of WellPoint Inc., leaving Berkshire with 3.5 million shares.

_ Selling 1.1 million shares of UnitedHealth Corp., leaving 3.4 million shares.

_ Selling 942,102 shares of home improvement chain Home Depot Inc. to leave Berkshire about 2.8 million shares.

The filing does not differentiate between investments Berkshire makes, investments any of its subsidiaries make, or investments Buffett himself makes.

In addition to its investments, Berkshire owns more than 60 operating companies, including furniture, insurance, jewelry and candy firms, restaurants, natural gas and corporate jet firms.