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.

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

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

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.