投资者的公式

即使你同意12%的回报是不可改变的，你仍然希望在未来能取得好的业绩。这可以理解。毕竟有很多投资者长期业绩很好。但是，你未来的业绩取决于三个变量：股票净资产与股票市场价格的关系、税率和通货膨胀率。

让我们算算净资产和市场价格。当股票一直在净资产价格销售时，非常简单。100美元的净资产，平均市场价格100美元，12%的公司盈利就给投资者产生12%的回报。（还要减去摩擦成本，在此我们先忽略不计。）如果股息发放率为50%，我们的投资者将拿到6美元的股息，并获得另外6美元的净资产增加。这一净资产的增加会体现在投资者所持有的股票市场价格上。

如果股票价格是净资产的150%，情况就不一样了。投资者会受到同样的6美元股息。但是这只相当于他150美金成本的4%而已。公司的净资产也会增加6%（达到106美元）。而投资者的股票市场价值在净资产150%的基础上也会增加6%（达到159美元）。但是，投资者的总回报，也就是净资产增值加上股息，才只有10%而不是公司内在的12%盈利。

当投资者低于净资产买入，这个过程正好相反。比如，如果股票价格是净资产的80%，同样的盈利和股息发放率将产生7.5%的股息回报（6美元除以80美元）和6%的净资产增值回报。总回报为13.5%。换句话说，你最好买打折的而不是高价的，这和常识告诉我们的一样。

战后，道琼斯工业指数股票的市场价格最低达到净资产的84%（1974年），最高达到过净资产的232%（1965年）。大多数时候，股票市场价格远超过100%的净资产。（今年春天早些时候，股票价格大约是110%的净资产）让我们假定未来这一比率在100%左右。这意味着股票投资者会获得12%的回报。至少，他们在税和通胀之前可以获得那么多。

税后回报

由于中美税制不同，在此不再翻译。但是可以用中国的20%股息税和0%的资本利得税算算。假设盈利50%分红，则100美元净资产发6美金股息。按中国20%税率，剩下4.8美元。总回报为10.8%，比巴菲特时代的7%左右税后回报要好。

巴菲特：《通货膨胀如何欺诈股票投资者》（十二）

The investor's equation

Even if you agree that the 12 percent equity coupon is more or less immutable, you still may hope to do well with it in the years ahead. It's conceivable that you will. After all, a lot of investors did well with it for a long time. But your future results will be governed by three variables: the relationship between book value and market value, the tax rate, and the inflation rate.

Let's wade through a little arithmetic about book and market value. When stocks consistently sell at book value, it's all very simple. If a stock has a book value of $100 and also an average market value of $100, 12 percent earnings by business will produce a 12 percent return for the investor (less those frictional costs, which we'll ignore for the moment). If the payout ratio is 50 percent, our investor will get $6 via dividends and a further $6 from the increase in the book value of the business, which will, of course, be reflected in the market value of his holdings.

If the stock sold at 150 percent of book value, the picture would change. The investor would receive the same $6 cash dividend, but it would now represent only a 4 percent return on his $150 cost. The book value of the business would still increase by 6 percent (to $106) and the market value of the investor's holdings, valued consistently at 150 percent of book value, would similarly increase by 6 percent (to $159). But the investor's total return, i.e., from appreciation plus dividends, would be only 10 percent versus the underlying 12 percent earned by the business.

When the investor buys in below book value, the process is reversed. For example, if the stock sells at 80 percent of book value, the same earnings and payout assumptions would yield 7.5 percent from dividends ($6 on an $80 price) and 6 percent from appreciation - a total return of 13.5 percent. In other words, you do better by buying at a discount rather than a premium, just as common sense would suggest.

During the postwar years, the market value of the Dow Jones industrials has been as low as 84 percent of book value (in 1974) and as high as 232 percent (in 1965); most of the time the ratio has been well over 100 percent. (Early this spring, it was around 110 percent.) Let's assume that in the future the ratio will be something close to 100 percent - meaning that investors in stocks could earn the full 12 percent. At least, they could earn that figure before taxes and before inflation.

7 percent after taxes

How large a bite might taxes take out of the 12 percent? For individual investors, it seems reasonable to assume that federal, state, and local income taxes will average perhaps 50 percent on dividends and 30 percent on capital gains. A majority of investors may have marginal rates somewhat below these, but many with larger holdings will experience substantially higher rates. Under the new tax law, as FORTUNE observed last month, a high-income investor in a heavily taxed city could have a marginal rate on capital gains as high as 56 percent. (See

"The Tax Practitioners Act of 1976.")

So let's use 50 percent and 30 percent as representative for individual investors. Let's also assume, in line with recent experience, that corporations earning 12 percent on equity pay out 5 percent in cash dividends (2.5 percent after tax) and retain 7 percent, with those retained earnings producing a corresponding market-value growth (4.9 percent after the 30 percent tax). The after-tax return, then, would be 7.4 percent. Probably this should be rounded down to about 7 percent to allow for frictional costs. To push our stocks-as-disguised-bonds thesis one notch further, then, stocks might be regarded as the equivalent, for individuals, of 7 percent tax-exempt perpetual bonds.