2012年伯克希尔股东会问答：
BECKY QUICK: This question comes from Scott Bondurant who is from Chicago, Illinois, and he's a shareholder.
And he asks, “Can you please elaborate your views on risk? You clearly aren't a fan of relying on statistical probabilities, and you highlight the need for $20 billion in cash to feel comfortable. Why is that the magic number, and has it changed over time?”
WARREN BUFFETT: Yeah. Well, it isn't the magic number, and there is no magic number.
I would get very worried about somebody that walked in every morning and told us precisely how many dollars of cash we needed to be, you know, secured at three sigma or something like that.
Charlie and I have had a lot of — we saw a lot of problems develop in an organization that expressed their risks in sigma, and we even argued sometimes with the appropriateness of how they calculated their risk.
CHARLIE MUNGER: It was truly horrible.
WARREN BUFFETT: And they were a lot smarter than we were. (Laughs) That's what's depressing.
But we both have the same bend of mind whereby we think about worst cases all the time, and then we add on a big margin of safety, and we don't want to go back to go.
I mean, I enjoy tossing those papers in the other room, but I don't want to do it for a living again.
So we undoubtedly build in layers of safety that others might regard as foolish, but we've got 600,000 shareholders and we've got members of my family that have 80 or 90 percent of their net worth in the company.
And I'm just not interested in explaining to them that we went broke because there was a one-hundredth of 1 percent chance that we would go broke and there was a — the remaining probability was filled by the chance of doubling our money, and I decided that that was just a good gamble to take.
We're not going to do that. It doesn't mean that much. We are never going to risk what we have and need for what we don't have and don't need. We'll still find things to do where we can make money, but we don't have to stretch to do it.
And it's my job — and Charlie thinks the same way. We don't have to talk about it much.
But it's our job to figure out what can really go wrong with this place and, you know, we've seen September 11th, and we've seen September of 2008, and we'll see other things of a different nature but similar impact in the future.
And we not only want to sleep well all those nights, we want to be thinking about things to do with some excess money we might have around.
So it is — if you're calibrating it in some mathematical way, I would say it's really dangerous. I could give you a couple examples on that, but unfortunately I've learned about them on a confidential basis.
But some really great organizations have had dozens of people with advanced mathematical training and make — and thinking about it daily, making computations, and they don't really — they don't really get at the problem.
So it's at the top of the mind, always, around Berkshire, and your returns in 99 years out of 100 will probably be penalized by us being excessively conservative, and one year out of a hundred, we'll survive when some other people won't.
Charlie?
CHARLIE MUNGER: Yeah, how do these super-smart people with all these degrees in higher mathematics end up doing these dumb things?
I think it's explainable by the old proverb that, “To a man with a hammer, every problem looks pretty much like a nail.” They've learned these techniques and they just twist the problem so they fit the solution, which is not the way to do it.
WARREN BUFFETT: And they have a lack of understanding of history, I would say.
One of the things — in 1962, when I set up our office in Kiewit Plaza, where we still are, it's a different floor, I put seven items on the wall. Our art budget was $7, and I went down to the library, and for a dollar each I made photo copies of the pages from financial history.
And one of those cases, for example, was in May of 1901 when the Northern Pacific Corner occurred, and it's kind of interesting in terms of being in Omaha because Harriman was trying to get control of the Northern Pacific, and James J. Hill was trying to control the Northern Pacific.
And unbeknownst to each other, they both bought more than 50 percent of the stock. Now, when two people buy more than 50 percent of the stock each, and they both really want it, they're not just going to resell it. You know, interesting things happen.
CHARLIE MUNGER: To the shorts.
WARREN BUFFETT: And in that paper of May 1901, the whole rest of the market was totally collapsing because Northern Pacific went from $170 a share to $1000 a share in one day, trading for cash, because the shorts needed it.
And there was a little item at the top of that paper, which we still have at the office, where a brewer in Troy, New York, committed suicide by diving into a vat of hot beer because he'd gotten a margin call.
And to me, the lesson — that fellow probably understood sigmas and everything and knew how impossible it was that in one day a stock could go from 170 to 1,000 to cause margin calls on everything else.
And he ended up in a vat of hot beer, and I've never wanted to end up in a vat of hot beer. (Laughter)
So those seven days that I put up on the wall — life in financial markets has got no relation to sigmas.
I mean, if everybody that operated in financial markets had never had any concept of standard errors and so on, they would be a lot better off.
Don't you think so, Charlie?
CHARLIE MUNGER: Well, sure. (Laughter)
WARREN BUFFETT: Here, have some fudge. (Laughs)
CHARLIE MUNGER: It's created a lot of false confidence and — now, it has gone away.
Again, as I said earlier, the business schools have improved. So has risk control on Wall Street. They now have taken the Gaussian curve and they've just changed its shape.
WARREN BUFFETT: Threw it away.
CHARLIE MUNGER: They threw it away. Well, they just made a different shape than Gauss did, and it's a better curve now, even though it's less precise.
WARREN BUFFETT: They talk about fat tails, but they still don't know how fat to make them. They have no idea.
CHARLIE MUNGER: Well, but they knew — they've learned through painful experience they weren't fat enough.
WARREN BUFFETT: Yeah. They learned the other was wrong, but they don't know what's right.
CHARLIE MUNGER: We always knew there were fat tails. Warren and I, in the Salomon meetings, would look over at one another and roll our eyes when the risk control people were talking.
金融市场上任何事情都可能发生。永远不要用杠杆、不要做空。杠杆也许可以加快进程，但不会改变结果，还会引入资产清零的风险。
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