I bought a company in the mid-90s called Dexter Shoe and paid $400 million for it. And it went to zero. And I gave about $400 million worth of Berkshire stock, which is probably now worth $400 billion. But I've made lots of dumb decisions. That's part of the game.

Diversification is a protection against ignorance. It makes very little sense for those who know what they're doing.

I mean, in terms of alternatives, some people have suggested for example that why don't we - why isn't America doing what Berkshire Hathaway is doing? Why isn't that a better deal for America?

I will do anything that is basically covered by the law to reduce Berkshire's tax rate. For example, on wind energy, we get a tax credit if we build a lot of wind farms. That's the only reason to build them. They don't make sense without the tax credit.

We have to live with the rest of the world. And it's a mistake, in my view. Trade has generally developed in this country. We actually export 12 or 13 percent of our GDP. It was only 5 percent in 1970. But it benefits us. It benefits the rest of the world. It doesn't benefit the steelworker maybe in Ohio. And that's the problem that has to be addressed, because when you have something that's good for society, but terribly harmful for given individuals, we have got to make sure those individuals are taken care of.

Ignore the stock market, ignore the economy, and buy a business you understand.

Look for companies with high profit margins.