MT518 Market-Side Securities Trade Confirmation

When MT518 is used

A trade has two sides to confirm. The client side runs from the broker to its client with the MT515 (and the client’s MT517 affirmation). The market side runs between the two parties that dealt with each other, typically two broker-dealers or a dealer and a bank, and that is the MT518. Both counterparties can send each other an MT518 and compare the two (mutual comparison), directly or through an ETC service provider. One party can also send an MT518 alone to allege a trade against a counterparty that has not confirmed it.

The sender is the executing party and the receiver its trade counterparty. On exchange trades cleared by a central counterparty, the market side is usually confirmed by the exchange or the clearing house, so the MT518 is most common for over-the-counter trades, for example in bonds.

Sequence B (CONFDET) carries the trade: trade date and settlement date (98a::TRAD and 98a::SETT, both mandatory), the deal price (90a::DEAL, mandatory), the direction (22H::BUSE), the payment type (22H::PAYM), at least one confirmation party (B1, CONFPRTY, usually the buyer and the seller), the quantity (36B::CONF) and the security (35B). For bonds add the number of days accrued (99A::DAAC) and, in sequence C3, the accrued interest amount (19A::ACRU).

Settlement details (sequence C) are optional but useful on the market side: the settlement chain in C1 tells the counterparty where to deliver or receive, and the amounts in C3 (DEAL, ACRU, SETT) are the figures both custodians’ instructions will be matched on. Once the confirmations agree, each side instructs its custodian: the seller with an MT543 (deliver against payment) and the buyer with an MT541 (receive against payment).

If the counterparty disagrees, it reports the status with an MT509, for example 25D::MTCH//NMAT with a reason such as DDEA (deal price) or DQUA (quantity). A wrong confirmation is cancelled with 23G CANC and 20C::PREV, then resent.

MT518 format: sequences and fields

Rules worth knowing

• Sequences A and B are mandatory, and B must contain at least one B1. A1, B2, C with C1 to C3, D and E are optional.
• When 23G is CANC, link the confirmation being cancelled with 20C::PREV in sequence A1.
• Each 19A amount qualifier sits in its own C3 occurrence. An exchange rate (92B::EXCH) needs the resulting amount (19A::RESU) in the same occurrence.
• Network validated rules on the settlement parties and alternate identifiers apply as in the MT515; rule numbers differ between releases, so search for the error code your interface reports.

MT518 example

Dealer BRKRAEADXXX sells EUR 2,000,000 nominal of a 4% bond (XS00ZAGT0013) over the counter to BRKRGB2LXXX at 99.25 on 20 October 2026, for settlement at the ICSD (ICSDLULLXXX) on 22 October with 97 days of accrued interest (30/360 from the 15 July coupon).

{1:F01BRKRAEADAXXX0000000000}{2:I518BRKRGB2LXXXXN}{4:
:16R:GENL
:20C::SEME//BRK518261020011
:23G:NEWM
:98C::PREP//20261020143000
:22F::TRTR//TRAD
:16R:LINK
:20C::TRRF//OTC-77841
:16S:LINK
:16S:GENL
:16R:CONFDET
:98A::TRAD//20261020
:98A::SETT//20261022
:90A::DEAL//PRCT/99,25
:99A::DAAC//097
:94B::TRAD//OTCO
:22H::BUSE//SELL
:22H::PAYM//APMT
:16R:CONFPRTY
:95P::SELL//BRKRAEADXXX
:16S:CONFPRTY
:16R:CONFPRTY
:95P::BUYR//BRKRGB2LXXX
:16S:CONFPRTY
:36B::CONF//FAMT/2000000,
:35B:ISIN XS00ZAGT0013
ZAGTRADER DEMO 4PCT 2029
:16R:FIA
:92A::INTR//4,
:98A::MATU//20290715
:16S:FIA
:16S:CONFDET
:16R:SETDET
:22F::SETR//TRAD
:16R:SETPRTY
:95P::DEAG//BRKRAEADXXX
:97A::SAFE//12345
:16S:SETPRTY
:16R:SETPRTY
:95P::REAG//BRKRGB2LXXX
:97A::SAFE//67890
:16S:SETPRTY
:16R:SETPRTY
:95P::PSET//ICSDLULLXXX
:16S:SETPRTY
:16R:AMT
:19A::DEAL//EUR1985000,
:16S:AMT
:16R:AMT
:19A::ACRU//EUR21555,56
:16S:AMT
:16R:AMT
:19A::SETT//EUR2006555,56
:16S:AMT
:16S:SETDET
-}

Line by line

BRKRGB2LXXX compares this with its own records (or its own MT518) and reports any difference with an MT509.

Then BRKRAEADXXX instructs delivery against payment (MT543) and BRKRGB2LXXX receipt against payment (MT541) for EUR 2,006,555.56.

All BICs, accounts and the ISIN are made up. The ISIN carries a valid check digit.

Common errors and rejects

1. Accrued interest differs

   Different day count conventions or coupon dates give different values in 99A::DAAC and 19A::ACRU, so the settlement amounts differ and the custodians’ instructions break on amount (DMON). Agree the bond’s static data before confirming.

   How to fix it

2. Price or quantity disagreement

   The counterparty answers with an MT509 with 25D::MTCH//NMAT and a reason such as DDEA (deal price) or DQUA (quantity). Check the deal on the trading platform, then cancel and resend the confirmation if yours is wrong.

3. Wrong settlement chain

   A delivering or receiving agent, account or place of settlement that differs from the counterparty’s standing instructions makes the later settlement instructions fail to match (ICAG, DEPT).

   How to fix it

4. MT518 sent to a client instead of an MT515

   Clients and their order systems expect the client confirmation MT515, with commission and the client’s account. An MT518 to a client is usually not processed.

ISO 20022

Swift’s MT and MX equivalence table (8 May 2024) lists no ISO 20022 equivalent for the MT518.

Category 5 messages were not part of the November 2025 end of coexistence for payments, and the MT518 remains available on FIN.

Related messages

• MT515Client Confirmation of Purchase or Sale
• MT509Trade Status Message
• MT517Trade Confirmation Affirmation
• MT541Receive Against Payment
• MT543Deliver Against Payment
• MT548Settlement Status and Processing Advice

• Unmatched instruction (NMAT)

Codes used in MT518

• TRAD
• DMON
• ICAG
• DEPT

MT518 questions

What is an MT518 message?

A market-side securities trade confirmation: the executing party confirms a trade to its trade counterparty, for example dealer to dealer, with the trade details and, where needed, the settlement chain.

What is the difference between MT515 and MT518?

The MT515 confirms a trade to a client (broker to investment manager). The MT518 confirms it to the market counterparty. One market trade can lead to one MT518 and several MT515s, one per client allocation.

What does it mean to allege a trade with an MT518?

To send your confirmation of a trade to a counterparty that has not yet confirmed it, so that it can recognise and confirm or dispute the trade.

What happens after the MT518?

Once both sides agree, the seller instructs its custodian with an MT543 and the buyer with an MT541 (or MT542 and MT540 for free of payment). The custodians’ instructions are matched at the CSD.

Is there an ISO 20022 equivalent for MT518?

Swift’s equivalence table lists none. The MT518 remains an MT message on FIN.