Buffett's Berkshire Hathaway reveals stake in Charter Communications, tweaks several holdings

Billionaire Warren Buffett's company has revealed a new stake in Charter Communications and made several other tweaks to its $108 billion U.S. stock portfolio.

Berkshire Hathaway Inc. filed an update on its portfolio with the Securities and Exchange Commission Thursday.

Berkshire said it owned 2.3 million shares of cable television provider Charter at the end of June.

Many investors like to copy Buffett's moves because of his remarkably successful record. But Berkshire's combined filing includes investments made by two other executives at the company, so it's not always clear whether Buffett made the decisions.

Berkshire also bought more shares of General Motors, Verisign, USG and IBM during the second quarter.

It reduced its stakes in DirecTV, Liberty Media and National Oilwell Varco. It also eliminated an investment in Starz.