Despite Buffett overseeing stakes in nearly four-dozen securities, the lion's share of Berkshire's invested assets have been put to work in seven top ideas.

Berkshire Hathaway stock is up a stunning 26% this year, while Warren Buffett has been on a selling spree and now has $325 billion in cash.

Although Occidental Petroleum is already a major holding of Berkshire Hathaway, the company purchased an additional 8.9 million shares of Occidental last

Since Warren Buffett became the CEO of Berkshire Hathaway ( BRK.A 0.80%) ( BRK.B 0.95%) in 1965, its stock has delivered a compound annual return of 19.8%. That would have been enough to turn a $1,000 investment into $42.5 million, whereas the same investment in the S&P 500 would have grown to just $325,053 over the same period.

After spending much of Q3 selling shares of various companies including BAC, Warren Buffet is back to taking major long positions.