2015年5月30日发表于央行观察

5月28日，中国股市暴跌，两市市值从27日的71.57万亿降至67.51万亿。乍一看大家会很诧异，想2008年4万亿出来的时候，全世界欢呼雀跃，中国的投资与物价（包括房价）也都上了个新台阶，可是股市这4万亿大波动怎么说有就有，说没就没呢？

想象一个新股民往股票帐户里打入了10000元，他可以有几种选择，一种是购买1000股市价为10元的股票，一种是以每股100元的价格购买100股市价为10元的股票。在买卖过程中，新股民的10000元流入到卖家的股票帐户，总的资金没有变化，但对公司市值影响十分不同，前者对公司市值没有影响，但后者则使公司的市值翻了10倍。如果这家公司有100万股，那么其市值就从1000万元突变为1亿元。人们不禁要问，这9000万元是怎么创造出来的？人们更会疑问的是，明明新股民只打入了1万元，为何创造了9000万的市值？

这种市值虽然用人民币元来衡量，但这并不是多少亿元的银行存款，也不是多少亿元的纸币，而只是用人民币标价的股票罢了。人们也可以用同样的方法估计全中国香蕉现货的市值，大米现货的市值，但变动较为缓慢，统计较为复杂，人们也并不会去关心大米价格的涨跌有没有让大米的价值蒸发，反而会理解为价格的起落。所以股票市值本身就是一个人为计算出来的量，如同把全国人民的体重加总起来算一个中国人民总重一样，总重降低说明大家减肥了，并不能说明谁从人间蒸发了，市值下跌也只能说明股价下跌了。

从货币的角度我们会看到，目前投保基金公布的股市保证金余额为2.4万亿，这些都可以随时转变成银行存款。我们可以想象如果所有人齐心协力，用这2.4万亿元买100股某家公司的股票，然后在这个价格上卖掉，再买另一家公司的100股，所有公司买过一遍之后，每家公司的股价都是240亿元每股，市场总市值可以嘉玲好多好多遍，但真正能够还原成银行存款的，也就还是原先的2.4万亿。股票毕竟不能用来当钱花。当大家都想卖股票持有保证金的时候，整个估值自然就下来了，但保证金还是那么多保证金。

而四万亿次刺激政策导致的结果是不一样的，因为银行通过贷款创造了等量的存款，货币总量（纸币+硬币+银行存款）和银行的信贷一起扩张，而这些存款都是可以用来买楼买包的。股市涨得再高，股民盈利再多，想要买房的话还是要卖股票，把保证金打回银行存款帐户， 72万亿市值的股票，在目前的房地产交易习惯下，最多也就能买2.4万亿元的房，而不可能买72万亿元的房。这和08年底到现在货币量从50万亿增长到现在130万亿对经济的影响是不一样的，这里增长的80万亿全都能用来买房。

所以28日股市大跌，市值减少了4万亿，对于货币量其实没有影响，钱并没有蒸发。保证金存款虽然在不同的股价上易手，但总量还是那2.4万亿，并没有减少。每个股民持仓的价值，只能被解读为“如果现在你卖的话能得到这些钱”，而并不是像钱包里的纸币那样“你有这些钱”。而当卖出股票得到钱的时候，其实都是从另外的一个人的口袋里给过来的钱，股票易手只是一个给钱的理由罢了，而并不是像银行结售汇那样，我把100美元纸币给银行，银行就给我620元人民币，如果好多人这样做，银行就能给出好几十万亿的人民币。股民是不可能从目前的股市中提出市值那么多的银行存款的。

但上述情形可以发生变化。股民可以用股票作为抵押，借出存款转为保证金入市，在这个过程中货币量会增加。注意，如果融资融券业务中，证券公司是把自己在银行的存款借给融资者，那么在银行看来货币总量并没有变化，只是存款从证券公司的帐户转移到了股民交易保证金帐户而已。如果新的货币（也就是银行存款）创造出来，在股票交易中流转给其他的人，而这些人并没有银行贷款要还，那么这些新创造出来的存款就会存在下去，即使最初的借款人不能归还借款，也还是如此。当然银行肯定不傻，股票都是打很低的折扣来抵押，同时还可以设置类似平仓价格的条款，在股价下跌的时候卖出，把其他股民的钱套过来，还借款股民的欠债。

另外，如果股票被直接用来买房或者别的资产，那么对房价的冲击就不再是2.4万亿元在起作用，而真的是70万亿元在起作用。持有500万元市值股票的股民，把500万元股票给了售房者以换得一套房子，这套房子也就真不是400万元存款能买得起的了。当然，这种事情在公司并购中早已十分常见，高市盈率公司借着股价奇高的时候，用股票买入便宜的公司，即使后来自己股价大跌，但对方公司已入自己囊中，其再有天大的意见也没用了，市场变了嘛。

Published on May 30, 2015, in Central Bank Observation

On May 28th, the Chinese stock market experienced a sharp decline, with the combined market capitalization of both markets dropping from 71.57 trillion yuan on the 27th to 67.51 trillion yuan. At first glance, many might be puzzled. In 2008, when 4 trillion yuan appeared, the world rejoiced. China's investments and prices, including real estate prices, reached new heights. However, why is it that the substantial fluctuation of 4 trillion yuan in the stock market is here one moment and gone the next?

Imagine a new stock investor depositing 10,000 yuan into their stock account. They have a few options: they can either buy 1,000 shares of a stock priced at 10 yuan each, or they can purchase 100 shares of a stock priced at 10 yuan each for 100 yuan per share. During the trading process, the new investor's 10,000 yuan flows into the seller's stock account. The total funds don't change, but the impact on the company's market capitalization is vastly different. In the former case, the company's market capitalization remains unaffected, but in the latter case, the company's market capitalization increases tenfold. If the company has a million shares, its market capitalization would shift from 10 million yuan to 100 million yuan. One might wonder, how was this additional 90 million yuan created? Moreover, why did the initial 10,000 yuan investment lead to a market capitalization increase of 90 million yuan?

This notion of market capitalization, while measured in Chinese yuan, isn't akin to bank deposits or physical currency in the billions. It's simply the valuation of stocks priced in Chinese yuan. Similarly, one could estimate the market value of all bananas or rice in China using the same method, but the changes are slower, the statistics are more complex, and people don't tend to concern themselves with fluctuations in rice prices causing the value of rice to evaporate. Instead, they understand that prices rise and fall. Thus, market capitalization of stocks is an artificially calculated quantity, similar to summing up the weights of all the people in a country to calculate the total weight of the population. A decrease in total weight doesn't imply anyone has evaporated, just as a decrease in market capitalization doesn't exclusively denote that value has evaporated.

From a monetary perspective, it's important to note that the current securities market margin balance disclosed by insurance funds is 2.4 trillion yuan, and these funds can be converted into bank deposits at any time. Consider if everyone collectively used this 2.4 trillion yuan to buy 100 shares of a company's stock and then sold at that price before buying 100 shares of another company's stock. After all companies have been purchased in this manner, each company's stock price would be 240 billion yuan per share. The market's total capitalization could be magnified many times, but the actual amount that can be converted back into bank deposits would still remain 2.4 trillion yuan. After all, stocks can't be spent like money. When everyone intends to sell stocks held as margin deposits, the overall valuation naturally decreases, but the amount of margin deposits remains unchanged.

The result of the 4 trillion yuan stimulus policy is different, because banks create an equal amount of deposits through loans. The total money supply (currency + coins + bank deposits) and bank credit expand together. These deposits can be used to buy real estate and other assets. No matter how high the stock market rises, how much profit stockholders make, if they want to buy real estate, they still need to sell stocks and convert margin deposits back to bank accounts. With the current practices in real estate transactions, stocks worth a total market capitalization of 72 trillion yuan could only purchase real estate valued at 2.4 trillion yuan, not 72 trillion yuan. This is different from the impact of the increase in the money supply from 50 trillion yuan in late 2008 to the current 130 trillion yuan on the economy, where the entire 80 trillion yuan increase could be used to buy real estate.

Therefore, the 28th's stock market crash and the reduction of 4 trillion yuan in market capitalization don't actually impact the money supply; the money didn't evaporate. Although margin deposits change hands at different stock prices, their total remains 2.4 trillion yuan and doesn't decrease. The value of each stockholder's holdings can only be interpreted as "if you sell now, you'll get this much money," rather than "you have this much money" like the physical banknotes in your wallet. When stocks are sold and money is received, the funds are essentially transferred from another person's pocket. The transfer of stocks is merely a reason to exchange money, unlike foreign exchange transactions where I give the bank 100 US dollars, and the bank gives me 620 Chinese yuan. If many people do this, the bank can issue several trillion yuan. Stockholders cannot withdraw such a substantial amount of bank deposits from the current stock market.

However, the situation described above can change. Stockholders can use stocks as collateral, convert deposits into margin funds, and expand the money supply in the process. Note that in margin trading and short selling, securities firms lend their deposits to borrowers. From the bank's perspective, the total money supply hasn't changed; only the deposits have shifted from the securities firm's account to the trader's margin account. If new money (bank deposits) is created and circulates among stock traders, without the need for repayment to banks, this newly created deposit can persist, even if the initial borrower can't repay the loan. Of course, banks are not naive; stocks are often mortgaged at steep discounts, and banks can set terms similar to closing prices. When stock prices fall, they can sell and bring in money from other traders, thereby repaying the debts of the borrowing traders.

Furthermore, if stocks are directly used to purchase real estate or other assets, the impact on property prices is no longer 2.4 trillion yuan, but rather a substantial 70 trillion yuan. A stockholder with stocks worth 5 million yuan could exchange those stocks with a real estate seller for a property, which a 4 million yuan deposit wouldn't suffice to buy. Of course, this kind of thing is already quite common in corporate mergers and acquisitions. Companies with high price-to-earnings ratios use their high stock prices to acquire cheaper companies. Even if their own stock price falls later, the acquired company remains theirs, rendering the latter's opinions irrelevant. After all, the market has changed.