A record year for suspicious trading
The FCA's latest Market Cleanliness Statistic shows abnormal share price movement before more than four in ten UK takeover announcements last year, the highest figure on record. We look at what is driving the rise and what it means for how you run your insider list.
The number
More than four out of ten UK takeover announcements in 2025 were preceded by suspicious share trading, according to the Financial Conduct Authority's annual report and accounts 2025/26. The figure rose to 41%, up from 37.8% in 2024 and 30.3% in 2023, and sits well above the five-year moving average of 33.7%. It is the highest reading since the FCA began publishing the measure.
A second FCA gauge moved in the same direction. The Abnormal Trading Volume measure, which flags unusual increases in trading ahead of a deal, rose to 8.1% in 2025 from 5.6% in 2024, based on 154 of the 1,898 takeover announcements reviewed. Two separate signals, pointing the same way, is not a coincidence a compliance officer can shrug off.
The FCA was measured in its own response. "The results suggest market integrity risks remain, particularly during periods of heightened volatility," it said, adding that it would keep focusing on detecting, deterring and disrupting financial crime to protect confidence in UK markets. Restrained language, for a record the regulator has now watched climb three years running.
What is behind the climb
Some of the rise is methodology, not misconduct. The FCA revised how the statistic is calculated in November 2024, adding intraday price data and a market comparison test designed to strip out the noise of general volatility. That change alone pushed the reported figure higher than under the old approach, and the regulator has been careful to say a like-for-like comparison only really holds from 2024 onwards.
That does not explain the trend on its own. The rise from 37.8% to 41% happened entirely under the revised methodology, so it reflects a genuine year-on-year deterioration, not a base effect from the recalculation. It also lands against a backdrop the FCA has flagged before: last year its co-head of enforcement and market oversight, Therese Chambers, issued a public warning to market participants about the leaking of sensitive deal information, and separate reporting has found a similar share of UK takeovers reaching the press before any official announcement (read more about this in our article here). Leaks and abnormal trading are not the same thing, but a deal that has already been guessed at in the papers is a deal where the circle of people who know something has already grown too wide. We covered the previous year's figures and what they meant for insider list management when the 2024 data came out, and the same practical lessons apply here, only more urgently.
Why it matters beyond the headline
The Market Cleanliness Statistic has real limits. It only captures positive price movements in the 48 hours before an announcement, it cannot tell a leak from a lucky analyst, and it says nothing about who was trading or why. The FCA is candid about all of this. What the figure is good at is showing direction of travel, and the direction has been consistently upward since a low of around 10% in 2018.
For a compliance team, that direction of travel is the real signal. A rising cleanliness statistic means the FCA has more reason, not less, to scrutinise who had access to price-sensitive information before a deal became public, and when. If your insider list cannot show, cleanly and to the minute, who was added, when their access started, and when it ended, that is the gap a regulator's question will land on. A record year for suspicious trading is a record year for the FCA asking companies to prove their controls worked, and "we think the list was accurate" is not proof.
This is where insider list discipline stops being a paperwork exercise and starts being the evidence that keeps a routine enquiry routine. InsiderList exists for exactly this moment: every addition, removal and access change timestamped automatically, so when a deal leaks or trades look abnormal, you can show the FCA precisely who knew what, and when, without reconstructing it from memory and email threads.
The takeaway
Suspicious trading ahead of UK takeovers has nearly quadrupled since 2018, and 2025 set a new high on two separate FCA measures at once. The regulator's language stayed calm, but the trend line has not, and it is the trend line, not any single year, that should shape how seriously you treat access control on your next deal.