10/22の記事では、銀行の貸出＝預金創造を左右するのは準備預金の量ではなく政策金利であるとのイングランド銀行の解説を紹介しました。
Money creation in the modern economy - Quarterly Bulletin article - YouTube
今回は欧州中央銀行（ECB）と国際決済銀行（BIS）の解説の再紹介です。まずはECBのConstâncio副総裁です。
ECB: Challenges to monetary policy in 2012
…, it is argued by some that financial institutions would be free to instantly transform their loans from the central bank into credit to the non-financial sector. This fits into the old theoretical view about the credit multiplier according to which the sequence of money creation goes from the primary liquidity created by central banks to total money supply created by banks via their credit decisions. In reality the sequence works more in the opposite direction with banks taking first their credit decisions and then looking for the necessary funding and reserves of central bank money.*1
In modern banking sectors, credit decisions precede the availability of reserves in the central bank. As Charles Goodhart pointedly argued, it would be more appropriate talking about a “Credit divisor” than about a “Credit multiplier”
「銀行の貸出判断が準備預金のアベイラビリティ」に先行するのであってその逆ではない、というものです。
Constâncioが引用しているBISのペーパーでは、準備預金のアベイラビリティは銀行貸出の制約ではないことが述べられています。
Unconventional monetary policies: an appraisal
In fact, the level of reserves hardly figures in banks’ lending decisions. The amount of credit outstanding is determined by banks’ willingness to supply loans, based on perceived risk-return trade-offs, and by the demand for those loans. The aggregate availability of bank reserves does not constrain the expansion directly. The reason is simple: as explained in Section I, under scheme 1 – by far the most common – in order to avoid extreme volatility in the interest rate, central banks supply reserves as demanded by the system. From this perspective, a reserve requirement, depending on its remuneration, affects the cost of intermediation and that of loans, but does not constrain credit expansion quantitatively. The main exogenous constraint on the expansion of credit is minimum capital requirements.
準備預金のアベイラビリティが制約にならないのは、"in order to avoid extreme volatility in the interest rate, central banks supply reserves as demanded by the system" すなわち、金利の激変を抑えるために需要に応じて準備預金を供給するためです。準備預金を調達できる金利の上限が分かっていれば、銀行は貸出に先立って市場の準備預金の量（の見通し）を気にする必要はありません。*2
なお、Fedが金利から準備預金（nonborrowed reseves）の量にターゲットを変更した際には、短期金利（FFレート）が激しく上下動しています。*3
SF Fed | How did the Fed change its approach to monetary policy in the late 1970s and early 1980s? |
In October 1979, under Chairman Paul Volcker, the FOMC changed its approach to monetary policy and began to target the quantity of money—specifically nonborrowed reserves. […] FOMC members expected that the new approach to monetary policy would result in greater volatility in the fed funds rate. This was indeed the result. […], the average fed funds rate fluctuated greatly between 1979 and 1982.
銀行の貸出が準備預金の量に制約されていないことは、事後のデータからも確認できます。
貸出と準備預金あるいは現金資産との間に、安定的な関係は見られません。住宅バブル期には、準備預金の減少が住宅価格上昇予想に基づく旺盛な貸出（借入）の制約になっていなかったことが明らかです。
量が貸出の制約になっていないことは、国債等を準備預金と交換する量的緩和が銀行の貸出余力を高めることにはつながらないことを意味します。
By the same token, under scheme 2, an expansion of reserves in excess of any requirement does not give banks more resources to expand lending. It only changes the composition of liquid assets of the banking system. Given the very high substitutability between bank reserves and other government assets held for liquidity purposes, the impact can be marginal at best.
「将来の金利」が変わらなければ、「将来の準備預金の量」を増額するアナウンスメント効果も期待できないことになります。将来の準備預金を増額するとアナウンスしても、ゼロ金利政策が続くだけなので、直接的には銀行の貸出にも借り入れ需要にも影響しないということです。