How to read the Bitfinex funding book
The funding book is the entire market state on one screen — every resting offer, every unfilled borrow bid, at every rate and term. Most lenders never open it, and most who do read it like a price chart. This guide is funding-book literacy: what each side means, where the FRR queue hides, and which patterns actually foreshadow rate moves (with honest error bars).
One screen, whole market
Open Funding → fUSD on Bitfinex (or pull /v2/book/fUSD/P2 from the public API) and you see two stacks: offers — lenders’ capital resting at asking rates — and bids — borrowers requesting funds at rates they’re willing to pay. Each row: rate (daily), period (2–120 days), and size.
Unlike a trading book, both sides are demands for the same currency at different prices of time. Every filled row becomes a live loan; the last matched price is the funding rate everyone quotes.
The three prices that matter
Best offer — the cheapest resting lender capital. This is what a borrower pays right now, and effectively the market rate. If your offer is above it, you are waiting for demand to come up and get you.
Best bid — the most a borrower is currently advertising to pay. The bid side is usually thin (most borrowing takes the best offer instead of advertising), so a thick, rising bid stack is itself information: urgent demand building below the surface.
The FRR — not a book level but an index of recent funding activity, shown as its own queue. Offers placed "at FRR" float with the index and fill in queue order. The FRR queue is where passive capital pools — which is precisely why FRR-passive lending underearns: it stands in the longest line at the average price.
Reading depth
Little supply resting above the current rate → a modest demand push travels far. Thin-above books are spike fuel; this is when a high resting offer is most likely to fill.
A wall of supply just over the market pins the rate — demand gets absorbed before it can print higher. Your above-market offer waits behind the wall.
Size accumulating on the borrow side, or the best bid climbing toward the best offer, foreshadows a push — demand that hasn’t executed yet.
What the book can and cannot tell you
We tested book features against three years of rate history. The honest scorecard:
- Imbalance leads the rate — modestly. Demand-vs-supply imbalance was the only book signal in our research that added predictive power beyond the rate’s own mean reversion. The effect is real but incremental; treat it as a tilt, not a trigger.
- Depth tells you fill probability, not direction. How much supply rests between the market and your price is a direct read on how likely your offer fills on the next push.
- Level-vs-history beats level-vs-gut. The book tells you what is; only the rate history tells you whether that is high or low for the regime. Percentile context does more work than any single book snapshot.
- The book cannot time spikes. The triggers are exogenous — price moves, liquidations. The book shapes how far a spike travels, not when it starts. Position accordingly (standing offers), don’t predict.
The practical takeaway
Book literacy improves two decisions: where to rest your offer (read the supply wall — just above it if thin, don’t queue behind a wall) and when to lean (a building bid stack in a thin-above book justifies a higher ask than usual). Neither requires staring at a screen — both reduce to rules a bot can hold around the clock, repriced as the book shifts. Which is the job description of a funding bot.
And one prophylactic note: the book is public, including your offers. Any floor price computable from public data can be undercut by a competitor resting one tick below it — which is why sophisticated lenders vary their pricing rather than parking at a famous round number.
Funding book FAQ
What do P0–P3 and R0 mean in the Bitfinex book API?
Aggregation levels. P0–P3 group orders into price buckets of increasing coarseness (P2 is a good default for reading structure); R0 is the raw, order-by-order book. Public endpoint, no key: /v2/book/fUSD/P2.
Why does my funding offer never fill?
Almost always: too much supply resting between the market rate and your price. Pull the book and sum the offer sizes below your rate — that whole wall fills before you do. Reprice relative to the wall and the recent rate distribution, not to a number you like.
Is placing offers "at FRR" a good default?
It is the passive default, and it structurally underearns: you stand in the longest queue at the average price and capture no spikes. Percentile-floor pricing above market — filled less often, at better rates — has dominated FRR-passive lending across our three years of backtests.
Rules beat staring
Everything in this guide compiles down to pricing rules — and rules are what bots are for. Stratum reprices against the live book and the rate history around the clock, non-custodially, on a flat fee.