Long XBTUSD Perpetual Contract Example

The following examples do not consider Premium, which is explained above.

XBTUSD Contract Details

Contract Value = 1 USD
Margin Currency = Bitcoin or XBT
Underlying Index = XBT BitMEX Index
Interest Quote Index = USD Lending Rate in the BitMEX Index (.USDBON)
Interest Base Index = XBT Lending Rate in the BitMEX Index (.XBTBON)
Funding Timestamp = 04:00 UTC, 12:00 UTC, and 20:00 UTC

Day 1, 10:00 UTC

A trader goes long 15,000 XBTUSD contracts at a price of 750 USD.

XBT Position Value = 15,000 Contracts * 1 USD * 1/750 = 20 XBT

Day 1, 12:00 UTC

The trader held the position over the Funding Timestamp at 12:00 UTC and exchanges the Funding Amount. The amount he pays is determined as follows:

The XBTUSD spot price is currently 750 USD.

Interest Quote Index = 1.00% per day
Interest Base Index = 0.25% per day

Funding Rate = (1.00% - 0.25%) / 3 = 0.25%

Funding Amount = Position Value * Funding Rate = 20 XBT * 0.25% = 0.05 XBT

The Funding Amount is positive, therefore since he is long the trader pays and his counterparty who is short receives 0.05 XBT.

Day 1, 18:00 UTC

The XBTUSD contract rose in price to 800 USD. The trader closes out his position by selling 15,000 XBTUSD contracts. He does this before the next Funding Timestamp at 20:00 UTC and will not need to pay the Funding Amount at that time.

The trader made 1.25 XBT profit from the increase in the value of XBTUSD:

PNL = 15,000 * 1 USD * (1/750 - 1/800) = 1.25 XBT

The trader exchanged 0.05 XBT in funding, hence the trader’s total profit is 1.2 XBT (1.25 XBT - 0.05 XBT).

Funding Rate Examples

Recall the formulas for calculating the Funding Rate:

Interest Rate (I) = (Interest Quote Index - Interest Base Index) / Funding Interval
Premium Index (P) = (Max(0, Impact Bid Price - Mark Price) - Max(0, Mark Price - Impact Ask Price)) / Spot Price +  Fair Basis used in Mark Price
Funding Rate (F) = Premium Index (P) + clamp(Interest Rate (I) - Premium Index (P), 0.05%, -0.05%)

Below is an example of how the Funding Rate (F) varies with varying Interest Rate (I) and Premium Index § figures.

Interest Rate (I)	Premium Index §	Funding Rate (F)
0.03%	0.00%	0.03%
0.03%	0.06%	0.03%
0.03%	0.15%	0.10%
0.03%	-0.05%	0.00%
0.03%	-0.10%	-0.05%
0.10%	0.06%	0.10%
0.10%	0.15%	0.10%
0.10%	-0.05%	0.00%
0.10%	-0.10%	-0.05%
0.20%	0.10%	0.15%
0.30%	0.10%	0.15%
0.45%	0.10%	0.15%