It was sometime in 2015, on a hiking trail in Hong Kong, that the perpetual swap — also called a perpetual future or a “perp” for short — was born. Quarterly futures, monthly futures, weekly futures, 48-hour futures, even a contract that lasted just 24 hours before resetting. You got exactly the spot price,’” Delo said. "We had to dynamically adjust how we calculated that funding rate," Delo said. What comes nextBitMEX chose not to patent the perpetual swap.