銀行是如何憑空創造錢的
經濟社會的大部分錢是以儲蓄的方式存在於銀行而不是通過紙幣或硬幣的形式流通在市場上。如果你從我這買走價值1000$的資產，那麼變動的僅僅是你的存款少了1000$，我的存款多了1000$。對於銀行來說，資金變動為零。
如果一年以後，你決定賣出該資產，我從你手中以2000$買回。那麼，這多的1000$是從哪裡出現的？這次交易是你的賬戶上多了2000$，我的賬戶上相應的減少同樣的資金。銀行的資金變化仍然是零。
法定準備金
如果沒有法定準備金的限制，那麼銀行就可以無限制的創造“錢”。商業銀行需要存儲一定比例的資金到央行（美國聯邦儲備系統）。
法定準備金對商業銀行印刷的人民幣數量有所限制。如果商業銀行需要存儲所接收儲蓄金額的10%在央行，那麼，它最大只能放貸這10%的十倍。
如果銀行一共收到100$的存款，那麼它可以放貸90$。借貸人就可以開具90$的支票。銀行又可以放貸81$（上面借貸人存在銀行的90$），這81$又會被存到銀行。
這個過程會一直持續到銀行沒有資金可貸。銀行最多可以放貸1000$：$90 +$81 + $72.90 + $65.61…..
央行
央行的最主要功能是維持國家貨幣的穩定性。央行通過提高和降低利率來遏制最主要的威脅：通貨膨脹。我們經常讀到關於聯邦儲備系統或是別國的央行提高、降低利率。但是，它們是如何做到的？央行可以通過提高或降低法定準備金率，但是央行很少這麼做。最受央行青睞的方法是公開市場業務。
公開市場業務
中央政府通過公開發行國庫券來籌集資金，並將該資金存於銀行系統。為了增加流動性（存款金額）央行會購買債券，從而增加商業銀行的存款。
如果央行要減少經濟的流動性，央行會出售所持有的債券。這似乎會顯得有點奇怪，但是其效果是減少了商業銀行的存款金額。央行通過出售債券所得的資金將不會放入商業銀行流通體系中。繼而，商業銀行會減少大約10倍於該筆金額的貸款組合。
貼現率
央行的貼現率是其利率政策的一個體現。當市場缺少流通性，商業銀行無力支付法定儲備金的時候，商業銀行便可以去央行的“窗口”按照貼現率借貸。央行的貼現率越低，商業銀行所貸的資金也就會越多。
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.
本文翻譯由兄弟財經提供
文章來源：http://www.incrediblecharts.com/economy/banking_system.php