On 6 July 2026, the Financial Conduct Authority published the Mills Review, its examination of how AI will reshape retail financial services in the UK. The review covers seven recommendations across the regulatory perimeter, oversight architecture, and the transition to autonomous decision-making. It names the accountability gap at the centre of autonomous AI trading. It does not close it.
This is the thirteenth piece in the Pre-Mortem series. Five questions, applied to the public record, before the outcome is known.
The Bet
UK firms deploying autonomous trading AI are betting that the Senior Managers and Certification Regime (SMCR), the framework that holds named executives personally accountable for conduct failures in their area of responsibility, covers their position through general senior manager oversight. The FCA has been clear that delegating a decision to an algorithm does not transfer senior manager liability to the algorithm. The bet is that this principle, correctly stated and on the public record, can be demonstrated in practice before an enforcement case defines what demonstrating it actually requires.
The Assumption
Seven recommendations. One question still without an answer:
When an autonomous trading system executes a decision at machine speed, without pausing for human approval of the individual trade, which specific senior manager function is accountable if that decision causes a customer loss, and what does demonstrating adequate oversight of a system like that actually require?
The Mills Review acknowledged the problem directly. Without guidance, the review found, the combination of greater opacity in AI-mediated decisions and factors such as model drift makes it harder for the regulator to identify a de facto responsible individual, or for senior managers to evidence meaningful human control. Stakeholder feedback throughout the review called for clearer guidance on what constitutes the “reasonable steps” expected of senior managers. The review recommends the FCA develop it. The FCA has not yet published it. Every firm currently deploying autonomous trading AI is operating on the assumption that its existing accountability structure covers the gap. That assumption has not been tested in an enforcement case.
The Sequence
December 2019. SMCR extended to all FCA solo-regulated firms, completing its rollout across financial services.
27 January 2026. The FCA launched the Mills Review, acknowledging that AI in retail financial services had developed faster than the regulatory frameworks designed to govern it.
24 February 2026. Call for input closed.
6 July 2026. The review published seven recommendations. The FCA committed to adapting its regulatory frameworks as the transition to autonomous models continues. No guidance named a specific senior manager function as accountable for autonomous trading decisions. No guidance defined what “reasonable steps” requires for a system executing at machine speed without human review of individual decisions.
The capability reached the market before SMCR was tested against it. The review arrived after the capability. The guidance has not arrived yet.
The Pager
The FCA has confirmed there will be no dedicated Senior Manager Function for AI, and that accountability falls on existing functions. That is a clear policy position and it deserves credit for being stated plainly. The Treasury Select Committee has urged the FCA to publish guidance specifying the level of assurance expected of senior managers for AI-related harm. The Mills Review carried that request forward into its recommendations. The harder question is the one seven recommendations did not answer: when an autonomous trading system causes a customer loss, which specific function holder carries the call?
The Proof
There are no enforcement cases. The first case will establish what “reasonable steps” means in an AI trading context. The Mills Review is a process measure: it produced recommendations. The outcome measure worth watching is whether the FCA’s follow-on guidance names a specific function and defines the oversight standard in operational terms rather than principles alone. A principle restated is not a gap closed.
Verdict
If the FCA’s follow-on guidance names the senior manager function accountable for autonomous trading AI and defines what “reasonable steps” requires at the operational level, UK financial services will have resolved an accountability gap that every other major jurisdiction is still navigating. The review’s existence, the named individual who led it, and the seven published recommendations are genuine evidence that the FCA identified the problem and moved on it. Without operational guidance, the gap stays open. The first enforcement case will write the rule in the least comfortable setting available. That is a considerably worse way to write it.