What is the difference between LACK and CLAC?

LACK means you are short: the account you deliver from lacks the securities. CLAC means the counterparty is short, so you, as the receiver, are waiting for them. The first needs action from you, the second needs a chase to the counterparty.

When does PEND LACK become PENF?

When settlement on the intended settlement date is no longer possible, normally at the end of the CSD’s settlement day for that date. From then on the account servicer reports :25D::SETT//PENF, and in the EU the CSD starts calculating cash penalties for each business day of the fail.

Can a PEND LACK instruction settle partially?

Only if partial settlement is allowed by the market and by both instructions. In T2S, partial settlement is controlled by the partial settlement indicator on the instruction. If it is allowed, the available quantity can settle and the rest stays pending, often with reason PART.

Why do I get LACK before the settlement date?

Many custodians check positions ahead of the settlement date and warn you as soon as the projected position will not cover the delivery. It is an early warning: nothing has failed yet.

Where is LACK in ISO 20022?

In sese.024, under SttlmSts/Pdg/Rsn/Cd/Cd while pending and under SttlmSts/Flng/Rsn/Cd/Cd once failing, with the value LACK.

Securities settlement

MT548 PEND LACK: pending for lack of securities

Written and maintained by ZagTrader. Last reviewed 21 October 2026. How this page is sourced and checked

:25D::SETT//PEND with :24B::PEND//LACK means your matched delivery is waiting because the account you deliver from does not hold enough available securities. Settlement on the intended date is still possible if the position arrives in time. If it does not, the status changes to PENF and the trade is failing.

What it means

An MT548 reports three separate things in its status blocks: whether the instruction was accepted (IPRC), whether it is matched (MTCH) and how settlement is going (SETT). PEND under SETT means the instruction is matched or does not need matching, and settlement on the intended settlement date can still happen. The reason in :24B::PEND// explains what it is waiting for.

LACK points at your side: the safekeeping account named in the instruction does not have enough deliverable securities. It is the delivering party’s problem. When you are the receiver and the deliverer is short, you see CLAC instead (counterparty insufficient securities). The pairing is the same for cash: MONY is your shortage, CMON the counterparty’s.

Many account servicers send LACK before the settlement date, as soon as their projection shows the position will not cover the delivery. On the settlement day itself the CSD retries the instruction in each settlement cycle while the position stays short. If the day closes without settlement, the next status is PENF with the same or a new reason (often still LACK).

In ISO 20022 the same information sits in sese.024 under SttlmSts/Pdg/Rsn/Cd/Cd = LACK, and later under SttlmSts/Flng when the instruction fails.

Common causes

The securities you are selling have not arrived yet: a purchase that should cover this sale is itself pending or failing (back-to-back trades). The account servicer may also show LAAW or LINK in that case.
The position is in the wrong account or at the wrong place of safekeeping: booked to a different safekeeping account, still held at another custodian, or not yet realigned between CSDs.
Part of the holding is not available: blocked for a corporate action you instructed on, pledged as collateral, out on loan or on a restricted sub-balance. Related reasons include SBLO, LALO and FROZ.
A short sale or an oversell: the trading system allowed a sale larger than the settled position.
A corporate action changed the holding (split, merger, ISIN change) and the instruction still names the old ISIN or quantity.
Partial settlement is not allowed (by your instruction or by market rules), so a position that covers only part of the quantity does not settle anything.

How to fix it

Check your own position in the safekeeping account named in :97A::SAFE: settled holding, blocked or pledged sub-balances, and pending receipts. Compare with the latest MT535 and the pending list in MT537.
If a covering purchase is still pending, chase that trade first. Fixing the receipt usually fixes the delivery. Consider linking the two instructions if your CSD supports it, so the delivery settles as soon as the receipt does.
If the securities sit in another account or at another custodian, move them now with an internal transfer or a free of payment delivery, and allow for the CSD’s cut-off times.
If part of the position is blocked or on loan, release the block or recall the loan, or agree a reduced or partial settlement with the counterparty. Partial settlement must be allowed on both instructions where the CSD supports it.
Tell the counterparty early. A receiver that knows the delivery will fail can plan funding and avoid its own onward fails.
If you will not have the securities on the settlement date, assume the trade will fail. In the EU a settlement fail penalty under CSDR is then charged for each business day the instruction stays unsettled; borrowing the securities may cost less. See failing settlement (PENF).

Example

The custodian CUSTGB2LXXX reports to ZagTrader Test Bank that its matched delivery against payment of 25,000 shares is pending on the settlement date because the safekeeping account holds only 20,000 available shares.

{1:F01CUSTGB2LAXXX0000000000}{2:I548ZAGTAEADXXXXN}{4:
:16R:GENL
:20C::SEME//ST26102200118
:23G:INST
:98C::PREP//20261022080500
:16R:LINK
:13A::LINK//543
:20C::RELA//ZT26102000021
:16S:LINK
:16R:STAT
:25D::MTCH//MACH
:16S:STAT
:16R:STAT
:25D::SETT//PEND
:16R:REAS
:24B::PEND//LACK
:70D::REAS//AVAILABLE 20000 REQUIRED 25000
:16S:REAS
:16S:STAT
:16S:GENL
:16R:SETTRAN
:35B:ISIN AEZAGT000016
ZAGTRADER TEST PJSC
:36B::SETT//UNIT/25000,
:19A::SETT//AED103750,00
:97A::SAFE//ZAG-SAFE-0001
:22F::SETR//TRAD
:22H::REDE//DELI
:22H::PAYM//APMT
:98A::SETT//20261022
:98A::TRAD//20261020
:16R:SETPRTY
:95P::PSET//CSDXAEADXXX
:16S:SETPRTY
:16R:SETPRTY
:95P::REAG//BRKRGB2LXXX
:16S:SETPRTY
:16S:SETTRAN
-}

Open this example in the parser

MTCH//MACH shows the instruction is matched, so the problem is the position, not the trade details.

SETT//PEND on the settlement date itself means settlement is still possible today. The reason block says why it has not happened yet.

The narrative in :70D::REAS is optional and its wording depends on the account servicer.

Questions

What is the difference between LACK and CLAC?: LACK means you are short: the account you deliver from lacks the securities. CLAC means the counterparty is short, so you, as the receiver, are waiting for them. The first needs action from you, the second needs a chase to the counterparty.
When does PEND LACK become PENF?: When settlement on the intended settlement date is no longer possible, normally at the end of the CSD’s settlement day for that date. From then on the account servicer reports :25D::SETT//PENF, and in the EU the CSD starts calculating cash penalties for each business day of the fail.
Can a PEND LACK instruction settle partially?: Only if partial settlement is allowed by the market and by both instructions. In T2S, partial settlement is controlled by the partial settlement indicator on the instruction. If it is allowed, the available quantity can settle and the rest stays pending, often with reason PART.
Why do I get LACK before the settlement date?: Many custodians check positions ahead of the settlement date and warn you as soon as the projected position will not cover the delivery. It is an early warning: nothing has failed yet.
Where is LACK in ISO 20022?: In sese.024, under SttlmSts/Pdg/Rsn/Cd/Cd while pending and under SttlmSts/Flng/Rsn/Cd/Cd once failing, with the value LACK.

Messages involved

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