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Spotlight PEPPOL BIS Billing 3.0 The EU e-invoicing mandate is here — France Sept 2026, Belgium Jan 2026, Germany 2025.

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MT508 — Intra-Position Advice

The intra-position movement advice. The custodian tells the client that a security has been reclassified between two account sub-compartments (available, blocked, dedicated collateral…) — with no change of ownership, but with an impact on operational availability.

Purpose

MT508 is issued when a security already held by the client undergoes an internal reclassification in the custodian's system, with no transfer of ownership. Typical use cases:

  • Collateral blocking — an available security moves into a "blocked-collateral" sub-account to pledge an MT504. No longer sellable until released.
  • Repo placement — move from the trading sub-account to the repo sub-account.
  • Bearer → registered conversion on the same security.
  • Post corporate-action awakening — release of a reserve dedicated to an optional dividend option after option expiry.
  • Regulatory segregation — segregated ↔ omnibus move to honour the client mandate (typically EMIR Article 39 for CCPs, or MiFID II segregation obligations).

MT508 is typically issued after the actual movement (post-mortem advice), for reconciliation. When the instruction is prior, it's the command that flows (sese.013 ISO 20022 or a custodian proprietary interface).

Sequence structure

  • GENL — General Information: reference, function, intra-position movement type (BLCO blocking, REOP reopening, SEGR segregation…), dates.
  • LINK — Linkages: link to a prior instruction (RELA) if applicable.
  • INTPOS — Intra-Position Movement: security, quantity, price, and two SUBSAFE (Sub-Safekeeping) sub-sequences: one with quantity OUT (source compartment), the other with quantity IN (destination compartment).
  • ADDINFO — explanatory narrative.

Block 4 tags

TagNameFormatUsage
:22F:Indicator:4!c/[8c]/4!cINTP//BLCO (blocking), INTP//REOP (reopen), INTP//SEGR (segregation), INTP//DSEG (de-segregation).
:98A:Date:4!c//8!nPREP, EFFD (effective date of the move).
:13A:Number Identification:4!c//3!cLINK//500 — linked MT type reference (here MT500 registrar instruction).
:35B:Instrument4*35xISIN of the security in scope.
:36B:Quantity:4!c//4!c/15dINTP (total intra-position), OUT (quantity out), IN (quantity in).
:97A:Account:4!c//35xSAFE — securities account and sub-compartment identifier (SUBPART/… notation).
:90A:Price:4!c//3!a/15dTBD (to-be-determined valuation reference) — market price at move date.

Real-world example

Euroclear Belgium (CSD) advises BNP Paribas (client) that 80,000 OAT 2032 have been reclassified from the "available" sub-account to the "blocked-collateral" sub-account, after the pledge for CSA-2024-001 (Deutsche Bank):

text mt508-blocking.txt 
{1:F01EOCXBEBBXXXX0000000000}{2:I508BNPAFRPPXXXXN}{3:{108:IPA20260520001}}{4:
:16R:GENL
:20C::SEME//IPA20260520001
:23G:NEWM
:22F::INTP//BLCO
:98A::PREP//20260520
:98A::EFFD//20260520
:16S:GENL
:16R:LINK
:13A::LINK//500
:20C::RELA//REG20260516001
:16S:LINK
:16R:INTPOS
:35B:ISIN FR0014007T87
OAT 0,50% 05/2032
:36B::INTP//FAMT/80000,00
:97A::SAFE//BNPP-CSD-001
:90A::TBD//EUR96,00
:16R:SUBSAFE
:97A::SAFE//SUBPART/AVAILABLE/EUROCLEAR-PT
:36B::OUT//FAMT/80000,00
:16S:SUBSAFE
:16R:SUBSAFE
:97A::SAFE//SUBPART/BLOCKED-COLL/EUROCLEAR-PT
:36B::IN//FAMT/80000,00
:16S:SUBSAFE
:16S:INTPOS
:16R:ADDINFO
:70E::ADTX//BLOCKING 80000 OAT32 FOR CSA-2024-001 COLLATERAL PLEDGE
:16S:ADDINFO}
  • :22F::INTP//BLCO — move type: blocking (reserve).
  • :98A::EFFD//20260520 — reclassification effective date (20 May).
  • :35B:ISIN FR0014007T87 — OAT 2032 concerned.
  • First SUBSAFE with :36B::OUT// — 80,000 out of "AVAILABLE" sub-account.
  • Second SUBSAFE with :36B::IN// — 80,000 into "BLOCKED-COLL".
  • Narrative :70E::ADTX// — explicit CSA-2024-001 reference for audit trail.

Common pitfalls

  • OUT ≠ IN — the sum of out and in quantities must be strictly equal (intra-position, no net variation). Any discrepancy indicates a custodian bug.
  • Unknown sub-compartment — the client must have declared sub-compartments in its ledger ahead. An unknown BLOCKED-COLL triggers an ETL reject.
  • Backdated EFFD — MT508 can be backdated up to 5 days; beyond, suspicion of manipulation.
  • No RELA / LINK — for a blocking linked to an MT500/MT504, always reference the original instruction via LINK. Without it, audit trail broken.
  • MT508 / MT540 confusion — MT508 = INTRA movement, no change of ownership. MT540 = real delivery to a third-party account, with change. Mixing them up biases custody positions.

ISO 20022 equivalent

  • semt.013 — Intra-Position Movement Confirmation (direct equivalent).
  • semt.015 — Intra-Position Movement Status Advice.
  • semt.014 — Intra-Position Movement Instruction (the command before the move).
  • MT500 — when the reclassification follows a registration instruction.
  • MT504 — when blocking serves a collateral pledge.
  • MT535 — Statement of Holdings, which will reflect updated compartments.
  • ISO 20022: semt.013, semt.014, semt.015.