Options

TL;DR

A MetaFlux option is a standard European, fully collateralized contract on a listed underlying. It trades through RFQ only. There is no option order book.

• The holder pays the premium at the fill. That is the whole requirement. An option position carries no margin, no mark price, and no liquidation.
• The writer locks the worst case at the fill. The lock is called the escrow. It stays in the series pot until the position closes or the series settles.
• A put settles in USDC. A call settles in the underlying coin. The denomination is on every row as settle_asset. Read it. A client that assumes dollars is wrong about every call.
• The chain never computes an option price and never needs an implied volatility. The premium is the price two accounts agree on in an RFQ.

Read the live series from option_series. Trade them with rfq_request, rfq_quote and rfq_accept.

The two kinds

A series is one (underlying, expiry, strike, kind) tuple. Exactly two kinds exist. S* is the settlement price and K is the strike.

Kind	Wire value	Payoff per whole unit	Escrow per whole unit	settle_asset
Put	"put"	max(K − S*, 0) USDC	K USDC	"USDC"
Call	"call"	max(1 − K / S*, 0) COIN	ONE coin	the underlying's token, e.g. "BTC"

Both are European. Neither can be exercised before expiry. A position closes early by trading it back, not by exercise.

Why a call escrows one coin

The call's denomination is forced, not chosen.

A cash call pays max(S* − K, 0) in USDC. The price has no ceiling, so that payoff has no finite worst case. No cash escrow can cover it. A cash call therefore needs a margin engine and a liquidation ladder for its writers.

Read the same payoff in the underlying and it is bounded at every price:

max(1 − K / S*, 0) COIN  valued at S*  =  max(S* − K, 0) USDC

K / S* is above zero, so 1 − K / S* is below one at every price. One coin per contract therefore covers the worst case, whatever happens to the price. That is the covered call every desk already writes, and it is why this lane keeps its central promise: both sides are fully funded at the fill, so an option position can never be liquidated.

A call is denominated in the coin, not in dollars

On a call series, escrow_per_unit is "1", the settlement payout is coin, and the writer's refund is coin. The number "1" is one coin, not one dollar.

Read settle_asset on the row and use it as the currency of escrow_per_unit, of option_state.escrow, and of every amount settlement moves. A caller that formats those figures as dollars is wrong by the whole asset class on every call.

The premium is the exception, and it is the one that is always USDC. See the premium is always USDC.

The payoff at a price

One BTC call, K = 100,000, settling at S* = 125,000:

payoff = max(1 − 100000 / 125000, 0) = 0.2 BTC per unit
refund = 1 − 0.2                     = 0.8 BTC per unit

The holder's 0.2 BTC is worth 0.2 × 125,000 = $25,000 at the settlement price, which is exactly S* − K. The coin payoff and the cash payoff are the same economics; only the currency the chain can safely escrow differs.

At S* = 100,000 or below the payoff is 0 and the writer takes the whole coin back.

The put is the plain one. One BTC put, K = 100,000, settling at S* = 90,000, pays the holder $10,000 and refunds the writer $90,000 of its $100,000 escrow.

What a fill moves

An option fill moves four things and nothing else.

1. The premium goes from the holder to the writer, in USDC, on both kinds.
2. The escrow goes from the writer's balance into the series pot, in settle_asset.
3. A closing writer's escrow comes back out of the pot, in settle_asset.
4. The taker pays a trading fee, in USDC. See the option fee.

An option fill opens no perpetual position and touches no margin figure. See what an option position is not.

A call writer must hold the coin. The escrow leaves the writer's spot balance of the underlying token. A spot balance cannot go negative, so holding the coin IS the whole collateral test: no margin figure is consulted and no USDC is encumbered. A writer short of the coin is refused with insufficient underlying balance for the escrow.

A call escrow cannot net the premium it earns. On a put series the incoming USDC premium reduces the USDC the writer must find for the escrow, so the chain checks one net number. On a call series the escrow is coin and the premium is dollars, so the chain checks the two assets separately: the coin for the escrow, then USDC for the fee. That is why a call writer can be refused with insufficient free collateral for the fee while holding every coin it needs.

Closing releases the escrow exactly. The strike sits on an escrow grid that the listing rule enforces, so the escrow per unit is a whole number of the settlement asset's smallest committed step. A partial close releases exactly that rate times the closed units. No rounding residue can build up on the trading path.

A holder who sells back closes first. The chain nets the two legs of each account before it locks anything: an account that holds long units and then writes gives up long units instead of opening a short. So a round trip returns exactly what it locked.

The premium is always USDC

settle_asset governs the escrow and the settlement payout. It does not govern the premium.

Amount	Currency on a put	Currency on a call
Premium (RFQ price × units)	USDC	USDC
Taker fee	USDC	USDC
Escrow	USDC	the coin
Settlement payout and refund	USDC	the coin

An RFQ price is a premium per whole underlying unit in USDC, on the 1e8 plane, for both kinds. Quote a call in dollars; read its escrow and its payout in coin. A client that divides the premium on the coin plane overstates it.

The option fee

Only the TAKER pays. The taker is whoever sent the RFQ request, so it can be the holder or the writer depending on which side they asked for. The quoting maker has no fee leg at all.

The fee is the SMALLER of two terms, and it is charged in USDC on both kinds:

fee = min( strike_face x taker_rate ,  premium x premium_cap )

strike_face is strike × size, for BOTH kinds. The strike face is the only notional the chain can read without pricing anything. A put's worst payout IS the strike face. A call escrows one coin, whose dollar worth the chain would have to fetch a price to know, so the strike face is the bound it uses there too.

The premium term is the tail guard. A far out-of-the-money option can have a premium far below its strike face, and the notional term alone would then charge a fee larger than the option itself. The cap holds the fee to a fraction of the premium the taker actually paid. It binds rarely — only when the premium is a sliver of the strike face — but that is exactly the case it exists for.

Both terms truncate toward zero, and the smaller one wins, so the fee never rounds up.

Both rates are governance parameters and both start UNSET, which charges nothing. The taker rate is capped at 1% of the notional by the same ceiling every other fee rate uses. Read the live values on /info fee_schedule, in the option row of products.

The size plane

RFQ size is an integer on the 10^sz_decimals plane of the series, exactly like a perpetual order size. sz_decimals is on every option_series row.

• Wire size = whole units × 10^sz_decimals.
• Premium in USDC = quoted price × whole units.
• Escrow in settle_asset = escrow_per_unit × whole units.

The premium is truncated toward zero to micro-USDC. A fill whose premium truncates to zero is refused, so a size that is too small for the quoted price does not trade for free.

Settlement

At expiry the chain settles the whole series in one block. It pays from the series pot, and the pot closes to exactly zero.

• Each holder is paid intrinsic × units, truncated toward zero.
• Each writer is refunded (escrow rate − intrinsic) × units, truncated toward zero.
• The rounding residue is dust. It goes to the insurance fund. It is never a charge on a writer beyond the escrow, and never a shortfall for a holder.

Every amount is paid in settle_asset. A put credits the ordinary USDC account balance. A call credits the spot balance of the underlying token — the same balance a spot trade moves. Dust routes to the insurance fund in that same asset.

A call's intrinsic divides by S*, so it truncates once more than a put's. The truncation always shrinks the holder's claim, which is the safe direction: the writer's refund is the complement, so a charge can never exceed the escrow.

The settlement price

The settlement price is the arithmetic mean of the committed oracle prices whose source timestamp falls inside a window that ends at expiry. It is not the last price, and it is not a mark price.

Samples are deduplicated by source timestamp. One oracle submission is one sample, however many blocks carry it forward. That is what keeps the mean independent of the block cadence.

The window needs a minimum number of distinct source timestamps before it can price. The defaults are below. Governance can vote each of them.

Knob	Default	Meaning
Window	180,000 ms	Length of the price window before expiry
Minimum entries	20	Distinct source timestamps the window needs
Widening step	one window per 60,000 ms after expiry	How fast a thin window grows
Maximum window	900,000 ms	Ceiling on the widened window
Abandon after	86,400,000 ms	Time after expiry at which the series gives up

Deferral and abandonment

Settlement can defer, and it can abandon

A thin window defers. If the window holds fewer than the minimum number of distinct source timestamps, the series does not settle. It waits, retries a minute later, and widens the window by one step each time. A series that can price always prices, however late the attempt.

A window that never fills abandons. Past the abandon bound the chain stops waiting. Nobody is paid. Every writer takes their whole escrow back — the whole coin on a call, the whole strike on a put — and a holder of an in-the-money option gets nothing. No price is honest at that point, so the chain moves no money on one.

Abandonment is a dead-feed backstop, not a normal outcome. It is the reason a series on a thinly fed underlying is a different risk from a series on a busy one.

What an option position is not

It has no	Because
Liquidation	Both sides are fully funded at the fill. There is nothing to liquidate
Margin requirement	The holder paid the premium. The writer locked the worst case
Mark price	The chain never prices an option
Order book	The lane is RFQ only. See RFQ
Maker fee	Only the taker pays. The quoting maker has no fee leg. See the option fee
Portfolio-margin offset	Options are outside portfolio margin
Early exercise	The style is European. A position closes early by trading, not by exercise
Spread or capped payoff	The chain lists single legs only. Build a spread from two series

Listing a series

A series is listed by a validator ⅔-stake vote, not by a user action and not by a permissionless deploy. The vote checks that the underlying is a live market with a fresh price feed, that expiry is at least one hour ahead, and that the strike sits on the escrow grid.

A call needs an underlying with a spot token. The escrow and the payout are one unit of the underlying, so an account must be able to hold that token. An index market has a price feed but no token of its own, so a call on it is refused with a call needs an underlying with a spot token. A put on the same underlying is fine: it escrows and pays USDC.

The chain caps how much of the lane one series or the whole registry can hold.

Cap	Value
Live series	1,024
Position rows per series	2,048
Position rows chain-wide	32,768

A fill that would open a new position row past either row cap is refused. Closing an existing row is always allowed.

Reads

Two public reads cover the lane.

Read	Answers
option_series	Which series are live, the signing_id to sign against, the settle_asset, and the escrow_per_unit a writer locks
option_state	What one account holds: units long, units written, and the escrow it has locked

A fill writes no ledger row of its own. Between the fill and expiry, option_state is the only read where a writer sees the escrow it locked and a holder sees its units.

A position row carries TWO planes and TWO currencies

long and short are unit counts, already on the series size scale. escrow is money, in that row's settle_asset — dollars on a put, coin on a call. All three are decimal strings, so a caller that reads escrow as units, or a call's escrow as dollars, gets a wrong number that still parses.

The account-wide option.escrow on account_state counts put legs only. It is one USDC number, and coins cannot be added to dollars. option.legs still counts every leg. For the per-series denominations read option_state.

There is still no public read for a series pot. The pot moves the same balances that account_state and the spot balances show leaving and returning.

What changed

The lane previously listed ceiling-bounded calls and settled everything in cash. That framing is gone. The bounded call is not a kind, it cannot be listed, and nothing on the chain can express a call spread any more.

Then	Now
kind was "put" or a third token	kind is "put" or "call", and nothing else
A call's payoff was bounded by a listed ceiling C, in USDC	A call's payoff is max(1 − K / S*, 0) COIN
A call escrowed C − K USDC — the width, not the strike	A call escrows ONE coin
The row carried a cap field on those calls	cap is gone, on the row and on the listing action
Every escrow and payout was USDC	The row carries settle_asset, and both follow it
The fee notional on a call was the width C − K	The fee notional is strike × size on both kinds
A call writer needed USDC	A call writer needs the coin

No series is converted. The last bounded-call series settled and retired before the change, so no live position crosses the boundary.

See also

• RFQ — the only way to trade an option
• option_series — the live series registry
• option_state — what one account holds in a series
• /exchange RFQ actions — the field tables and the typed-data primary types
• Oracle prices — the price source settlement reads
• MIP-4 — the proposal this product came from