Bitcoin perpetual contract takes bitcoin price as the trading index, so how to ensure the price difference between the contract price and the spot price is consistent? As the futures contract has a delivery date, the closer it is to the delivery date, the futures price in the market will naturally move closer to the spot price and eventually remain consistent. However, perpetual contract is a special futures contract. Unlike traditional futures, perpetual contracts have no expiration date and settlement date, so the price of perpetual contracts is unconstrained and can be arbitrary.

At this time, something called "cost of capital" appeared, which can be used to anchor the spot price. When the perpetual contract price and the spot price deviate from the reasonable spread at a certain moment, the cost of capital will forcibly pull the deviation spread back to a reasonable level. There are curious netizens asking questions:

How did the cost of capital pull the difference back?

Before answering this question, let's explain the concept of CoinEx capital cost.

The capital fee is not the fee charged by the exchange, but paid between long and short positions, which makes the transaction price close to the spot index price. The positive or negative capital rate determines which party needs to pay. Simply put, CoinEx does not charge any capital fees, and the money is transferred from one user to another.

When the capital rate is positive, multiple users (that is, the buyer of the contract) pay the capital fee to the empty user (the seller of the contract); If the fund rate is negative, empty users pay multiple users. When the capital interest rate is 0, neither long nor short parties need to pay the capital fee.

In short, when the contract premium, the capital ratio is positive, and the contract buyer needs to pay the seller. CoinEx will also narrow the spread between the contract market and the spot market, bring the price back to the normal level, and also limit the malicious manipulation of the contract price. If there is no roller coaster price difference, there is no harm.

For your intuitive understanding, let's give another example, or take the perpetual bitcoin contract as an example: it is reasonable to assume that the price difference between the perpetual bitcoin contract price and the spot price is between -20 and 20 points. At this time, Zhang San, as the buyer of the contract, maliciously raised the price of the perpetual contract, so that the price difference expanded to 100. At 24 o'clock that day, the actual price difference was too outrageous. At this time, Zhang San will compensate the investor who holds the empty order (that is, the seller of the contract), and the system will also deduct it from Zhang San's realized income. Therefore, in the perpetual contract, the higher the price, the greater the price difference, and the greater the compensation of the empty party.

How is the capital ratio valued?

CoinEx has three collection times of fund fees, namely (HKT) 08:00, 16:00 and 24:00. Simply put, users only need to pay or collect capital fees when holding positions at 8:00, 16:00 and 24:00 every day. If you close your position before the handling fee is charged, you don't need to pay the capital fee ~

For the current fund interest rate of each settlement, the fund interest rate calculated one minute before the last settlement time is taken.

The calculation formula is as follows:

Capital ratio = clamp (MA ((depth weighted buying price+depth weighted selling price) /2- spot index price)/spot index price-interest), a, b)

PS:

*MA stands for moving average, and CoinEx's fund rate will be calculated by taking the deeply weighted buying and selling price and spot index price in a certain period before each calculation.

* Interest is currently 0.

* perpetual contracts of *BTCUSD, BCHUSD, ETHUSD, LTCUSD, BSVUSD, XRPUSD and EOSUSD: a=-0. 1%, b=0. 1%.

* Depth-weighted purchase price = average price of "profit impact" of bidders.

* Depth-weighted selling price = average price of "profit impact" of competing sellers.

* Margin impact refers to the total value of a certain number of handicap orders.