The essence of overnight reverse repurchase or overnight positive repurchase is overnight repurchase. The so-called overnight repurchase actually refers to one day, and overnight repurchase actually refers to one day repurchase. Generally, the repurchase period is not stipulated in reverse repurchase or positive repurchase, but in fact, the repurchase itself will stipulate its trading period when the transaction is established, and the overnight reverse repurchase actually stipulates the repurchase period. It must be noted that there is a time limit for repurchase. When the reverse repurchase began to operate, it did put liquidity into the market, but when the reverse repurchase expired, it took liquidity away from the market. When the amount of reverse repurchase is less than the maturity of reverse repurchase, it will produce the result of extracting liquidity.

Federal funds in the United States refer to the interest rate in the inter-bank lending market in the United States and its main overnight (repo) lending rate. When the federal funds rate is low, it shows that the market is full of cheap funds. Because banks can easily obtain low-cost funds from the market to use, they need to control the related costs of other channels that can obtain funds, which will be indirectly transmitted to the savings interest rate.