How it settles
From trade to maturity, one market. The numbers in the middle come from four real days of SOL funding.
Swap floating funding for a fixed rate.
Perp funding flips between longs and shorts, sometimes within a day. Tack swaps SOL-PERP funding for a fixed rate to a weekly maturity: a basis trader locks in what the hedge earns, a speculator takes a view on where funding goes.
SOL: 50 sign changes in daily funding, 117 negative days, average +3.61% APR.
SOL perp · daily funding, APR · log scale · drag the water
Phoenix hourly data · 19 Nov 2025 – 1 Oct 2026
10 months of funding on a $100,000 SOL hedge.
Hold spot SOL, short the perp. The short receives funding while it is positive and pays it while it is negative. This is what that leg did on Phoenix from 19 Nov 2025 to 1 Oct 2026, one day at a time.
- Day
- 19 Nov 2025
- Funding that day
- +24.3% APR
- Sign changes so far
- 0
- Received so far
- +$67
Down $1,165 at the low point and +$3,137 at the end. A fixed leg pays the rate agreed at the trade, whatever the floating leg does.
Yellow line: an example 5% fixed rate, not a quote. Grey lines: the same hedge on the BTC and ETH perps.
Who pays what
Replaying SOL funding · 19 Nov 2025
Pay fixed
Long
Pays 5% fixed, receives floating. Comes out ahead when funding averages above 5%.
A view that funding will rise.
This replay, $100,000$0
Receive fixed
Short
Receives 5% fixed, pays floating. A basis trader already short the perp receives floating there, so the two cancel and 5% is left.
A hedge that wants a known rate.
This replay, $100,000$0
Long, at each checkpointN × (ΔF − K × Δt)Short: the negative
Point at a term to read it.
A market
One market per maturity. The floating leg is Phoenix's SOL perp funding, read from its account on chain. The fixed leg is the rate each trade is struck at.
- Funding
- Phoenix SOL perp
- Maturity
- Fridays, 08:00 UTC
- Settles in
- USDC
A trade
A maker posts a whole lot: notional N, fixed rate K, and collateral. A taker accepts the lot as it stands and locks collateral for the other side. The long pays K and receives floating; the short does the reverse.
Long $100,000 · pays 5.00%Short $100,000 · receives 5.00%
Checkpoints
Phoenix records SOL funding every hour, and each record goes on chain as a checkpoint, in order and without gaps. Here, one a day keeps the numbers readable.
- 2 Jun+20.70%
- 3 Jun+7.98%
- 4 Jun+3.10%
- 5 Jun−19.62%
Lazy settlement
Nothing moves at the marks themselves. Settlement applies every checkpoint since the position's last, in order: N × (ΔF − K × Δt) each. Anyone can send it; Tack's crank does after every update.
| Day | Floating | Fixed | Long |
|---|---|---|---|
| 2 Jun | +$56.72 | −$13.70 | +$43.02 |
| 3 Jun | +$21.87 | −$13.70 | +$8.17 |
| 4 Jun | +$8.50 | −$13.70 | −$5.20 |
| 5 Jun | −$53.74 | −$13.70 | −$67.44 |
| Applied in one step | −$21.45 | ||
$100,000 notional, 5% example rate, SOL funding 2 Jun–5 Jun 2026. The short gets the opposite.
Margin
Both sides lock USDC. Opening takes the larger of 25% of notional and twice a stress loss: the fixed rate plus a 100% move in funding, over the time left. Below maintenance at any checkpoint, the position closes there.
2 × $100,000 × (5% + 100%) × 21/365 = $12,082
$25,000
Bar: twice the stress loss as maturity nears. Mark: the 25% floor. Opening takes the larger.
Maturity
New trades stop an hour before maturity. Phoenix's record for the hour that ends at maturity settles the last stretch, and each side withdraws its balance.
Backtest a fixed rate
Pick a perp, a side, a rate and a window. Settlement runs on the same months of Phoenix funding. No Tack market existed then; this is what the swap would have paid.
Perp
Side
Window
DecJan 2026FebMarAprMayJunJulAugSepOct
SOL · 23 Mar 2026 – 21 Apr 2026 · 720 hours · $100,000 notional
Net for the short
+$398- Fixed leg, 5.00%
- +$411
- Floating leg, averaged +0.16%
- −$13
- Break-even fixed rate
- +0.16%
Fixed 5.00%
Day went the short's way Day went against itBars run from the fixed rate to that day's funding.