Crypto Newbie / Simulators / Funding Rate
Funding Rate Simulator — Perpetual Premium Mechanics
Perpetual contracts have no expiry — what stops the perp price from drifting forever from spot? Funding rate. Every 8 hours, longs and shorts exchange a payment scaled by the premium between mark and index price. This is the most powerful mean-reversion mechanic in crypto markets — and the basis for one of the biggest institutional arb strategies (cash-and-carry).
Mark vs Index price
Premium (mark / index − 1)
+0.316%
Computed funding rate
Per 8h window
+0.3258%
Per day (3 windows)
+0.977%
Annualised APR
+356.7%
Market bias signal
⚠ Extreme long bias — everyone long, perp dramatically over-bid. Mean-reversion signal historically.
Position payment over hold period
Long position pays
-$97.74
Short position receives
$97.74
Cash-and-carry arbitrage (delta-neutral)
Hold spot long + short perp. Directional moves cancel; pure funding yield remains. Common institutional play during high-positive-funding regimes.
Capital required
$11.00k
Net funding earned
$97.74
Net P&L (assumes hedge holds)
$97.74
APR equivalent
324.31%
Premium = the perp's bias signal
Premium = (mark price − index price) / index price. When perp trades above spot (premium > 0), longs are out-bidding shorts. The funding rate goes positive to PUNISH longs and ENCOURAGE shorts — paid every 8 hours, proportional to position size. The crowd is forced to rebalance. Sustained positive funding over days is a strong signal that retail is dramatically over-leveraged long; institutional traders treat this as a contrarian entry.
The cash-and-carry trade
Hold spot BTC long. Short the same notional in BTC perp. Your delta exposure to BTC price = zero (gains and losses cancel). But you collect the funding payment from the perp short. When funding is +0.05%/8h, that's +18% APR equivalent. With ~30-40% positive funding regimes during bull tops, the trade has yielded 50-100% APR for institutions. The catch: requires real capital on both legs and access to good leverage on the short.
Funding rate caps
Most venues cap the per-window funding rate at ±0.75% per 8h (or ±2.25% per day, or ~821% APR). When the cap is hit, the perp can't quickly rebalance to spot — premium can persist for days. This is when arbitrageurs make the most money: cap-locked funding means a near-guaranteed yield on the cash-and-carry, until the premium naturally decays as more arbitrageurs pile in.
Why retail should care even if not arbing
If you're long perp during sustained positive funding, you're paying the funding cost. A long held for 7 days during +0.05%/8h funding loses 1.05% just to funding — on top of any directional P&L. Many retail traders 'win' on direction but lose on funding over multi-day holds. The simulator's APR calc shows this: a 4.5%/year funding-only cost means a 4.5% directional gain breaks even.
Frequently asked questions
+Who actually receives my funding payment when I'm long and pay it?
Other traders on the opposite side, pro-rata. The venue acts as a clearinghouse: when funding is +0.05%/8h, ALL longs send 0.05% of notional, ALL shorts receive 0.05% of notional. The venue doesn't profit from funding directly (unlike taker fees) — it's a peer-to-peer redistribution.
+Why does the funding rate sometimes look 'wrong' compared to the premium?
Two reasons: (1) The cap clips extreme premia. A 3% premium might only produce 0.75% funding (capped). (2) The interest rate component (small, ~0.01% per 8h) is added on top. The simulator above shows the clean formula without venue-specific tweaks.
+Can funding rate go negative? When?
Yes — when the perp trades BELOW spot. This means shorts are over-bid (everyone's positioned for a drop). Funding flips negative, longs RECEIVE funding from shorts. This happens during panic sell-offs or after big liquidation cascades. Historically, sustained negative funding has been a strong bottom signal.
+Is the cash-and-carry arb really risk-free?
Close but not exactly. Risks: (1) Basis risk — if the perp permanently de-pegs from spot, your hedge fails. (2) Exchange risk — if the venue goes insolvent (FTX) your collateral is lost. (3) Liquidation risk on the perp leg if margin gets thin during volatility. (4) Funding can flip negative mid-trade. Real institutional desks run cash-and-carry with strict risk limits and multiple-venue diversification.
+Why does my position care about funding even at low leverage?
Funding is paid on NOTIONAL, not margin. A $10k notional perp position with 10x leverage = $1k margin. If funding is 1% per day, that's $100/day funding on your $10k notional — which is 10% of your $1k margin every day. The leverage multiplies the funding burden relative to your equity. This is why high-leverage holders rarely survive multi-day positive-funding regimes.