​What Warren Buffett is buying and selling

OMAHA, Neb. - Billionaire Warren Buffett's company unloaded its 41 million shares of Exxon Mobil (XOM) and sold a smaller stake in ConocoPhillips (COP) as oil prices fell last fall.

Berkshire Hathaway (BRK.A) filed an update on the stocks it held at the end of 2014 with the Securities and Exchange Commission Tuesday.

Berkshire recorded a number of moves during the last three months of last year, including buying 15.6 million shares of Deere & Co. (DE) stock and adding nearly 6.5 million shares to its already sizable IBM (IBM) holdings.

Many investors watch the filings closely because they 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.