Funding Rate Explained

How BULK's hourly funding payments actually work, with a worked example — because "funding rate" is one of those terms everyone nods along to without quite knowing what number to expect. For the formal specification, see docs.bulk.trade/bulk-exchange/funding.

Why funding exists at all

A perpetual contract has no expiration date, which raises an obvious question: what keeps its price from drifting away from the actual spot price of the underlying asset? Funding is the answer. It's a direct, periodic payment between long and short position holders, sized specifically to pull the perpetual's price back toward the spot price whenever it drifts.

The mechanics

Funding settles hourly, on the hour. The rate is calculated from the gap between BULK's own order-book price and the external oracle price (this gap is called the "premium"), smoothed over time via a moving average rather than reacting to a single instantaneous reading. That smoothed premium is compared against a configurable interest rate baseline, and the whole thing is capped in both directions so a temporary extreme dislocation — like the kind described in The BTC Liquidity Event (September 2026) — can't produce a runaway funding rate that punishes traders disproportionately for something outside their control.

Which way does money flow?

Positive funding → longs pay shorts.
Negative funding → shorts pay longs.

The payment is peer-to-peer — it moves directly between the traders on each side of the market. BULK doesn't take a cut of funding payments; the exchange isn't a party to this transaction, just the venue where it happens.

A worked example

Say BULK's BTC-USD order book has been trading at a slight premium to the oracle price for the past several hours — buyers are slightly more aggressive than sellers, pushing the local price up relative to the reference. That premium feeds into a positive funding rate for the next hourly settlement. If you're holding a long BTC-USD position when that settlement hits, you pay a small percentage of your position's notional value to the short side of the market. Hold the same long position through several consecutive positive-funding hours, and those payments compound — which is exactly why funding rate is a real, ongoing cost to factor into how long you expect to hold a position, not just a footnote.

Why this matters for your strategy

Holding a directional position through a period of consistently one-sided funding is a real, compounding cost (or, if you're on the right side of it, a real, compounding benefit) — check the current rate before assuming a "free" long-term hold.
A hedged position (see Understanding Portfolio Margin) that's long one asset and short a correlated one may pay funding on one leg while receiving it on the other — worth understanding both legs, not just the net margin benefit.
Funding is unrelated to trading fees — you can pay zero maker fees and still pay meaningful funding costs on a held position.

Why funding exists at all

The mechanics

Which way does money flow?

A worked example

Why this matters for your strategy

See also