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XRP Ledger Protocol Reference
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Transaction Reference
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Transaction Types
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AMMCreate
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AMMCreate

[Source]

(Requires the AMM amendment)

Create a new Automated Market Maker (AMM) instance for trading a pair of assets (fungible tokens or XRP).

Creates both an AMM entry and a special AccountRoot entry to represent the AMM. Also transfers ownership of the starting balance of both assets from the sender to the created AccountRoot and issues an initial balance of liquidity provider tokens (LP Tokens) from the AMM account to the sender.

Caution: When you create the AMM, you should fund it with (approximately) equal-value amounts of each asset. Otherwise, other users can profit at your expense by trading with this AMM (performing arbitrage). The currency risk that liquidity providers take on increases with the volatility (potential for imbalance) of the asset pair. The higher the trading fee, the more it offsets this risk, so it's best to set the trading fee based on the volatility of the asset pair.

Example AMMCreate JSON

{
    "Account" : "rJVUeRqDFNs2xqA7ncVE6ZoAhPUoaJJSQm",
    "Amount" : {
        "currency" : "TST",
        "issuer" : "rP9jPyP5kyvFRb6ZiRghAGw5u8SGAmU4bd",
        "value" : "25"
    },
    "Amount2" : "250000000",
    "Fee" : "2000000",
    "Flags" : 2147483648,
    "Sequence" : 6,
    "TradingFee" : 500,
    "TransactionType" : "AMMCreate"
}

AMMCreate Fields

In addition to the common fields, AMMCreate transactions use the following fields:

FieldJSON TypeInternal TypeRequired?Description
AmountCurrency AmountAmountYesThe first of the two assets to fund this AMM with. This must be a positive amount.
Amount2Currency AmountAmountYesThe second of the two assets to fund this AMM with. This must be a positive amount.
TradingFeeNumberUInt16YesThe fee to charge for trades against this AMM instance, in units of 1/100,000; a value of 1 is equivalent to 0.001%. The maximum value is 1000, indicating a 1% fee. The minimum value is 0.

One or both of Amount and Amount2 can be tokens; at most one of them can be XRP. They cannot both have the same currency code and issuer. The tokens' issuers must have Default Ripple enabled. If the Clawback amendment is enabled, those issuers must not have enabled the Allow Clawback flag. The assets cannot be LP tokens for another AMM.

Special Transaction Cost

Since each AMM instance involves an AccountRoot ledger entry, an AMM ledger entry, and a trust line for each token in its pool, an AMMCreate transaction requires a much higher than usual transaction cost to deter ledger spam. Instead of the standard minimum of 0.00001 XRP, AMMCreate must destroy at least the incremental owner reserve amount, currently 2 XRP. This is the same special transaction cost as AccountDelete transactions.

Error Cases

Besides errors that can occur for all transactions, AMMCreate transactions can result in the following transaction result codes:

Error CodeDescription
tecAMM_INVALID_TOKENSEither Amount or Amount2 has a currency code that is the same as this AMM's LP Tokens would use. (This is very unlikely to occur.)
tecDUPLICATEThere is already another AMM for this currency pair.
tecFROZENAt least one of the deposit assets (Amount or Amount2) is currently frozen.
tecINSUF_RESERVE_LINEThe sender of this transaction does meet the increased reserve requirement of processing this transaction, probably because they need a new trust line to hold the LP Tokens, and they don't have enough XRP to meet the additional owner reserve for a new trust line.
tecNO_AUTHAt least one of the deposit assets uses authorized trust lines and the sender does not have authorization to hold that asset.
tecNO_LINEThe sender does not have a trust line for at least one of the deposit assets.
tecNO_PERMISSIONAt least one of the deposit assets cannot be used in an AMM. For example, the issuer has enabled Clawback support.
tecUNFUNDED_AMMThe sender does not hold enough of the assets specified in Amount and Amount2 to fund the AMM.
terNO_RIPPLEThe issuer of at least one of the assets has not enabled the Default Ripple flag.
temAMM_BAD_TOKENSThe values of Amount and Amount2 are not valid: for example, both refer to the same token.
temBAD_FEEThe TradingFee value is invalid. It must be zero or a positive integer and cannot be over 1000.
temDISABLEDThe AMM feature is not enabled on this network.