DEEP LOOK | As TradFi and DeFi draw closer, the post-trade world is asking a pointed question: will convergence mean fewer standards, a convergence of standards, or just the mounting cost of maintaining too many?
The question sounds abstract. It isn’t. As settlement cycles compress from T+2 to T+1 and the industry looks beyond that towards T+0 and atomic settlement, the data richness, uniformity and consistency required to operate at speed and scale comes sharply into focus. Standards either enable that journey or slow it down. In the view of Paul Fullam, chair of ISITC and senior business consultant at FIS, one in particular is doing both simultaneously and the industry holds the key.
The problem with having two of everything
Fullam is talking about the coexistence of ISO 15022 and ISO 20022, the two messaging standards that continue to run in parallel across securities markets. Unlike payments, which formally ended its own coexistence period in November 2025 when Swift closed the door on MT messages, securities has no equivalent deadline. The community, or institutions that collectively own Swift as a cooperative, has not called time.
The cost of that inertia sits inside a mechanism that is easy to miss from a distance: coexistence rules require that anything added to ISO 20022 must also be replicated in ISO 15022. The effect is to cap the richer standard to fit the constraints of the older one. In corporate actions—Fullam’s specialism—the everyday illustration is a reference number. ISO 15022 allows 15 or 16 characters. ISO 20022 allows up to 35. But because the two must move in lockstep, even firms running 20022 natively constrain themselves to the shorter length to stay interoperable across the market. Multiply that across character sets, field lengths and ISO 20022’s use of XML extensions, and the result, Fullam says, is an industry paying to develop richer infrastructure.
The doubling shows up in maintenance too. ISITC’s own corporate actions working group submitted around eight or nine US change requests for the 2027 standards cycle, covering data elements the market genuinely needs. Under coexistence, those changes have to be replicated across both standards. Europe adds a similar tranche. Asia adds its own. Each enhancement is effectively done twice. “We’re double dipping,” Fullam says.
Where standards are, in fact, converging
Against that picture, there are areas where the standards environment is moving in a more coherent direction, and where ISITC is directly involved.
One of these areas is the Financial Markets Standards Board’s (FMSB’s) Standard for Sharing of Standard Settlement Instructions (SSIs), published in final form in January 2025, with updated ISO 20022-based taxonomies and templates released in June 2026. These updates, designed in conjunction with ISITC through its Reference Data Working Group, aim to reduce the manual processing and inconsistent formats that make SSI errors the leading cause of settlement fails after inventory shortfalls. On 30 June 2026, the EU T+1 Industry Committee, whose stakeholders include market infrastructure providers, market users, and experts from various financial sectors, announced its recognition of the updated standard as the minimum EEA data standard—a meaningful signal that the market is willing to align around a single approach.
The distinction matters. Where a standard can be established fresh—as did with SSIs—the industry can build cleanly on ISO 20022 from the outset. The coexistence problem is a legacy problem: the cost of a decision made when migration from ISO 15022 seemed manageable in parallel rather than requiring a clean break.
The T+1 and digital assets test
The question is whether accelerating settlement timelines will change the calculus. The EU’s T+1 deadline is 11 October 2027. The securities lending and repo markets, which depend on an extended settlement cycle for the mechanics of their core business, are already working through the implications of workarounds in a compressed environment. Each workaround has a cost in instruction amendments and manual intervention. Adding the overhead of a dual-standard environment to that picture concentrates minds on what is genuinely essential infrastructure and what is legacy maintenance.
Beyond T+1, the direction towards atomic settlement and digital assets raises longer-horizon questions about data precision and consistency that 15022 was not built to carry. Swift’s own tokenised asset interoperability trials have integrated ISO 20022 messaging with blockchain-native platforms — while still running ISO 15022 alongside. In its January 2026 article on the multi-bank tokenised bond settlement trial, Swift explicitly framed running both standards together as the mechanism that “unlocks scalability.” The implication is striking: the infrastructure Swift is building for the digital asset era currently depends on the continued existence of the dual-standard environment that Fullam argues needs to end. The architecture of the next era of settlement is being built on the assumption that ISO 20022’s richer data model is the foundation. The implication is that coexistence, as a permanent state, becomes progressively more anomalous.
Fullam is careful not to overstate the digital assets angle: he does not claim specialist expertise in how those markets will ultimately interact with corporate actions messaging. But the structural argument holds regardless. Where digital assets demand data precision and field lengths that older message formats cannot carry without truncation, the tipping point he has been describing once enhancements flow only to ISO 20022, data the market needs will eventually exist only in the newer standard, and firms still on 15022 will be missing it; at that point migration happens by necessity rather than mandate.
Who makes the call
Swift’s response to migration questions is consistent: it is a community concern, and the community must decide on the cost and feasibility of running two standards. That framing is correct as far as it goes. Swift is a cooperative, owned by the same institutions absorbing the cost of dual maintenance. The body with the authority to freeze ISO 15022 is the same community currently paying not to.
ISITC’s position—that maintenance on 15022 should stop, with all future enhancement directed to 20022—is designed to let that tipping point arrive by market logic rather than regulatory decree. Fullam is wary of an externally imposed deadline, not least for smaller participants still contentedly running older formats for whom a mandated migration would be disproportionate. The industry, he argues, should make that call itself.
Whether shorter cycles and digital assets become the forcing function for a decision the community has deferred for two decades is the live question. The convergence of TradFi and DeFi may not deliver fewer standards. But it is making the case, slowly and expensively, for one fewer than the industry currently maintains.
