UK Takeovers & Leaks: How Banks Must Tighten MAR, Takeover Code Compliance

The recent disclosure by the Financial Conduct Authority (FCA) that roughly 42 out of 110 (≈38-40 %) takeover announcements involving UK-listed companies were pre-empted by media leaks has escalated concerns among large corporate clients about confidentiality in M&A processes. This trend correlates with parallel findings that nearly the same proportion of takeover targets experienced abnormal share price rises in the two days preceding deal announcements in 2024—implicitly signaling potential insider trading or at least market sensitivity to leaked information.

One of the core drivers of leakage appears to be the sheer number of individuals (or “permanent insiders”) involved in any given deal. In earlier FCA studies (2019 and 2022), although the number of insiders had fallen, it still hovered at ~250-450 in large banks; in some past cases more than 600 people—even those in compliance, risk, or support functions—had full access to inside information, despite only a small subset working directly on the transaction.

Clients are responding strategically by asking banks to reduce disclosure scope and internal insider lists to “need-to-know” basis only. Boutique advisory firms are leveraging their smaller teams as a comparative advantage in confidentiality. However, empirical evidence suggests some companies may also use leaks purposely—to attract competing bidders, fend off unwanted ones, or influence the share price before formal offer announcements. “Strategic leaks” are of particular concern to regulators.

Regulatory enforcement is intensifying. In March 2025, the FCA issued Primary Market Bulletin 54 warning of increases in material leaks in live M&A transactions and reminding participants of obligations under MAR and the Takeover Code. The Takeover Panel is also “going harder on leakage.” Penalties for breach include unlimited fines, injunctions and, in certain cases, prohibition from regulated activity.

Strategic implications for investment banks include reputational risks, legal exposure, and client loss if perceived as inadequate in maintaining secrecy. Banks may need to invest in more rigid internal controls, refine insider access policies, deploy technological tools for information barriers, and possibly rebrand around confidentiality.

Open questions remain: What are the best practices to identify the source of leaks (bankers vs. issuers)? Is leak attribution sufficiently precise to enforce penalties? Will foreign bidders adapt to UK norms or be penalized for unfamiliarity? To what extent will these pressures—regulatory, client, competitive—reshape the structure of M&A advisory services in London?