Berkshire Hathaway Inc. (A) (BRK.A-N)

Main difference is the price. The As are a really high price, and the Bs are in the $300s. They're largely economically equivalent. The B shares were created in 1996 so that small investors could buy the stock without being taken advantage of by firms charging management fees for ETFs holding BRK.A. If you had a massive amount of money, like institutional investors, you'd be indifferent. Most people prefer the B shares. 

A great defensive holding. Very durable over the long term. Has had a pretty strong runup, so the valuation is more robust that it's been. People have fled to safety because of the banking crisis in the US. Insurance, especially, is counter-cyclical. You want to wait.

Warren Buffett just released his annual shareholder letter--essential reading on Wall Street. The S&P was down 18% last year, but Berkshire was up 4%. Annual compound gains since 1965: 9.9% S&P vs. 19.8% Berkshire. He has always recommend Berkshire stock, because they make long-term bets on the underlying business. The business, not the stock is what Buffett invests in. Berkshire is the top shareholder of 8 S&P stocks, like Chevron, Amex and Coke. Lessons: diversification, long-term thinking and compounding.

Kingpin of quality and investing. Interestingly, he also owns its top 3 holdings: AAPL, BAC, and CVX. Good quality companies with ability to sustain earnings over the long term. 30x earnings, not a great buy. Cherry-pick companies instead.