Spreader

This page covers how Spreader works its two legs, which markets can pair, each field in the ticket, how the ticket fills in the spread limit, what the order sheet shows, how a Spreader ends, what you can change while it runs, and what it does when something goes wrong.

What Spreader does

Spreader works two legs on the same exchange account. The lead is the market and side you picked in the ticket. The hedge is the opposite side of a second market with the same base asset.

Aura prices the lead off the hedge's book so the spread between them stays within your spread limit: Max spread when you buy the lead, Min spread when you sell it. The hedge then covers what the lead filled. The hedge always follows the lead, so the spread limit is best effort.

Which markets can pair

Both legs trade on the same account, on the same exchange, in the same base asset, and they must be different markets.

Aura does not compare the two legs' quote currencies. If they differ, the spread limit bounds a ratio of prices quoted in two currencies, and any exchange rate between them is yours to account for.

How it works

The spread

The spread is measured in basis points of the hedge price: (lead price ÷ hedge price − 1) × 10,000.

When you buy the lead and sell the hedge, the spread must stay at or under your Max spread. When you sell the lead and buy the hedge, it must stay at or over your Min spread. A negative limit means buying the lead below the hedge price, or accepting a sell below it.

Pricing the lead

The hedge price Aura counts on is the hedge's bid when you buy the lead, and its ask when you sell it. The limit turns that into the Implied lead price: the hedge price × (1 + limit ÷ 10,000). The ticket shows it live from the hedge's book.

• A Post lead rests like Chase. It rests at the more passive of Chase's own price, your Lead limit price, and the implied lead price, and requotes as either book moves.
• A Take lead sends IOC orders like Sniper, but only while it can cross the lead's book within the implied lead price. It never pays past it.

The lead's orders are never larger than the size showing at the hedge's best price, and they are sized so the hedge can cover them in whole lots of the hedge market.

The spread now

The spread now is what the lead would get this moment: its price at the touch it trades at, against the hedge price above. A Post lead trades at its own side (its bid when you buy), and a Take lead at the far side (its ask when you buy).

The limit starts empty. At its top right, Now 3.4 bps shows the spread now, rounded to a tenth of a bp so the lead reaches its touch: up for Max spread, down for Min spread. Click it to set the limit to that figure. A Post lead then joins its touch, and a Take lead takes it at once.

• The limit does not follow the market. Click Now again to take the spread of that moment.
• The limit stays when you change the side, the hedge market, or the lead's Post / Take.
• Now shows once both books have arrived. The order can't be sent until the limit has a value.

The hedge follows

The hedge covers what the lead has filled, less any fee the exchange took in the base asset, in whole lots of the hedge market.

• A Take hedge sends an IOC on each lead fill.
• A Post hedge rests like Chase, at or just inside its best price, and is enlarged as the lead fills.

The hedge has no price limit of its own. A taking hedge that fills after the book moved lands the realized spread past your limit by that move.

The lead ahead cap

The Lead ahead cap bounds how much the lead may have filled or resting beyond what the hedge has covered. When the lead reaches its cap, it waits for the hedge to catch up.

Never one leg alone

The lead posts only while both legs' books and trading rules are live. When the hedge's book goes away, Aura pulls the resting lead order.

Balances

On a spot leg, each order is kept within what your available balance can pay for, as in Chase. A hedge that pays with what a spot lead delivers, such as a hedge selling the BTC a buying spot lead receives, is never limited this way: it has to follow the lead's fills. A lead on an OKX or Bybit perpetual is kept within your margin, as in Chase. Its fills open a position rather than deliver coins, so a spot hedge behind it is kept within the balance it pays with. A hedge on a perpetual is never limited.

Aura does not check balances across the two legs. Set up the legs so the lead can trade from what you already hold. If the lead needs what the hedge would deliver, for example selling a spot lead whose base asset you do not hold, the exchange rejects the lead for insufficient balance.

When a spot hedge pays with a coin your available balance cannot cover for the whole quantity, the ticket says so under the Hedge row. An example is selling BTC you do not hold behind a perpetual lead. The exchange would reject the hedge, and the order would stop with Needs attention · Hedge leg can't be traded, leaving what the lead filled unhedged. The warning never stops you from placing the order.

Parameters

The ticket's Legs section holds the two legs. Each leg has a Post / Take toggle.

Lead ahead cap, Lead limit price and Post only sit under More options, a row that reads them back, for example "Ahead cap 0.1 BTC · Lead limit None · Post only Off". Click it to open them. While one of them can't be sent, the row is outlined in red.

The automatic Lead ahead cap is rounded down to the lead's lot, and is at least the larger of the two legs' minimum order sizes.

Below the submit button, Est. lead fee and Est. hedge fee estimate each leg's fee. A Take leg uses your taker rate. A Post leg uses the maker rate with Post only on, and a maker-to-taker range without it. The button reads, for example, "Buy BTC-USDT / Hedge BTC-USDT.PERP" until you enter a quantity.

While it runs

The order sheet

The headline shows:

• Filled: the lead's fill against the quantity.
• Avg fill: the lead's average price.
• Realized spread: the spread the two legs' fills realized, in bps, with your limit under it, for example "Limit ≤ 5 bps".
• Fees: what both legs paid, in bps of both legs' filled value, with the share of both legs' fills that filled as maker. When the two markets are quoted in different coins, the hedge's fee shows apart, for example "+ 1.41 USDT hedge", with no bps. While a leg has filled and its fee isn't known yet, Fees shows — rather than the other leg's fee alone.

The Legs row replaces the fill meter. It draws one bar per leg against the quantity:

• The lead's bar shows what filled and what rests. While the order works, a mark across it shows where the lead ahead cap stops the lead. Hover the bar to read the cap as a share of the quantity.
• The hedge's bar shows what it covered, with any unhedged amount hatched in amber.

Its lines say how hedged the order is: Unhedged … in amber, Fully hedged, or Nothing filled yet. While it works, a second line reads Lead at its cap, waiting for the hedge or Lead … under its cap. Before it starts it reads Not started, while cancelling Cancelling both legs, and when the order needs attention Needs attention.

Beside Max spread or Min spread in the Order card, a note shows the spread the lead would get right now, for example Now 6.1 bps. It turns amber once the spread is past your limit. There, a Post lead rests behind its touch and a Take lead does not fire. The Order card also lists the Hedge market.

After a Spreader finishes, the TCA column shows the realized spread against the mid spread at arrival, and the spread net of fees against crossing both books at arrival. See Execution cost.

How it ends

The status chip shows the outcome: filled, cancelled or part. cancelled. It reads rejected only for an order above your Max USD notional or one that never reached the exchange because the account had no connection. Every Spreader ends with a summary of what was unhedged, what was hedged, and the realized spread. For a filled or cancelled order, hover the status to read it. For other ends, it appears in the red box at the top of the order sheet. The Legs row also reads Ended fully hedged, Ended with … unhedged, or Ended with nothing filled.

Needs attention

When the hedge cannot be traded, Aura stops both legs and marks the order needs attention. The order sheet shows Needs attention · Hedge leg can't be traded. This happens when the exchange rejects the hedge for good, when its risk or margin controls cancel a hedge order, or after 5 hedge rejections in a row. A rate limit never does: the hedge waits and sends again. Nothing more is sent on either leg, and whatever the hedge did not cover stays unhedged. See Managing orders.

Amending

Open the order and click Amend, or click the pencil on its row in Open Orders. In the Order column you can change:

The Hedge market, Lead leg, Hedge leg, Post only and the reduce-only switches are fixed and stay dimmed.

Click Apply to send only what you changed, or Discard to leave without sending anything. Aura cancels the resting orders on both legs, checks the new values the way it checks a new order, and starts both legs again. What the hedge already covered stays covered. A lower cap holds the lead back until the hedge catches up.

What can go wrong

Spreader works in the base asset only, so a quote-currency budget does not apply. If your exchange account disconnects, see Connection status. To compare Spreader with the other algos, see Choosing an algo.