银行是如何凭空创造钱的
经济社会的大部分钱是以储蓄的方式存在于银行而不是通过纸币或硬币的形式流通在市场上。如果你从我这买走价值1000$的资产，那么变动的仅仅是你的存款少了1000$，我的存款多了1000$。对于银行来说，资金变动为零。
如果一年以后，你决定卖出该资产，我从你手中以2000$买回。那么，这多的1000$是从哪里出现的？这次交易是你的账户上多了2000$，我的账户上相应的减少同样的资金。银行的资金变化仍然是零。
法定准备金
如果没有法定准备金的限制，那么银行就可以无限制的创造“钱”。商业银行需要存储一定比例的资金到央行（美国联邦储备系统）。
法定准备金对商业银行印刷的人民币数量有所限制。如果商业银行需要存储所接收储蓄金额的10%在央行，那么，它最大只能放贷这10%的十倍。
如果银行一共收到100$的存款，那么它可以放贷90$。借贷人就可以开具90$的支票。银行又可以放贷81$（上面借贷人存在银行的90$），这81$又会被存到银行。
这个过程会一直持续到银行没有资金可贷。银行最多可以放贷1000$：$90 +$81 + $72.90 + $65.61…..
央行
央行的最主要功能是维持国家货币的稳定性。央行通过提高和降低利率来遏制最主要的威胁：通货膨胀。我们经常读到关于联邦储备系统或是别国的央行提高、降低利率。但是，它们是如何做到的？央行可以通过提高或降低法定准备金率，但是央行很少这么做。最受央行青睐的方法是公开市场业务。
公开市场业务
中央政府通过公开发行国库券来筹集资金，并将该资金存于银行系统。为了增加流动性（存款金额）央行会购买债券，从而增加商业银行的存款。
如果央行要减少经济的流动性，央行会出售所持有的债券。这似乎会显得有点奇怪，但是其效果是减少了商业银行的存款金额。央行通过出售债券所得的资金将不会放入商业银行流通体系中。继而，商业银行会减少大约10倍于该笔金额的贷款组合。
贴现率
央行的贴现率是其利率政策的一个体现。当市场缺少流通性，商业银行无力支付法定储备金的时候，商业银行便可以去央行的“窗口”按照贴现率借贷。央行的贴现率越低，商业银行所贷的资金也就会越多。
The Banking System
How Banks Create Money out of Thin Air
Most money in the economy is held in the form of deposits with banks rather than in the form of notes or coins. If you purchase an asset from me for $1000, payment is normally effected by reducing your checking account by $1000 and increasing my account by $1000. The net change in bank deposits is zero.
If one year later, you decide to sell the asset and I purchase it back from you for $2000, where does the additional money come from? The transaction this time increases your account by $2000 and reduces my account by the same amount. The net effect is still zero.
The bank can loan me the extra $1000 simply because there is a corresponding deposit of $1000 in another account. It does not matter if the deposit is not with the same bank; the clearing system offsets all transactions between banks and any temporary shortfall is made up by inter-bank loans.
Reserve Requirements
The banks could keep on creating "money" indefinitely if it were not for reserve requirements. The central bank (the Fed in the US) requires that commercial banks hold a certain percentage of their deposits as reserves, on hand or on deposit with the central bank.
Reserves place a limit on the amount of money that commercial banks can create. If 10% of deposits are required to be held as reserves, the banks can lend a maximum of ten times the amount deposited.
If the bank receives a deposit of $100 it can lend out $90. The borrower can then write a check for $90 which is deposited by someone else. The bank can lend another $81 (against the $90 deposit) which is again deposited.
This process continues until the amount that can be loaned is exhausted. The limit is $1000: $90 +$81 + $72.90 + $65.61 and so on.
The Central Bank
The primary function of most central banks is to protect the integrity of the nation's currency. The chief threat is inflation and the central bank attempts to control inflationary forces by raising and lowering interest rates.
We often read of the Fed or some other central bank raising or lowering interest rates but how does it do so? It could raise or lower the reserve requirements for central banks but this is seldom used. The favored method is through open market operations.
Open Market Operations
The central government raises funds through its treasury which normally sells bonds via auction in the open market. The proceeds are held on deposit with the banking system.
To increase liquidity (the amount of deposits) in the economy, the central bank will purchase bonds on the open market, thereby increasing deposits with commercial banks.
If the central bank wants to reduce liquidity in the economy, it will sell some of its bond holdings in the open market. This may seem a bit strange at first sight but the effect is to reduce deposits with the commercial banks. Bond purchasers have to pay the central bank which does not deposit the funds back in the commercial banking system. The effect is that banks have to reduce their loan portfolio by roughly ten times the amount withdrawn from the system.
The Discount Rate
The discount rate set by the central bank is an indication of their interest rate policy. Its only practical application is when the market is short of liquidity and commercial banks are unable to meet their reserve requirements. They then have to go to the "window" at the central bank and borrow funds overnight at the discount rate. The lower the discount rate is, the more likely banks are to borrow from the central bank to make up any shortfall.
本文翻译由兄弟财经提供
文章来源：http://www.incrediblecharts.com/economy/banking_system.php