RE: Fasten Seatbelts!16 Feb 2026 15:01
In the UK market, an institutional buyer wanting a 10% stake (932 million shares) cannot simply hit the "Buy" button on a million-pound order without gapping the price up instantly. They use two primary methods to stay "stealthy"...
Iceberg Orders (On-Book)...This is what you see in the summary as 2,000,000-share blocks. An "Iceberg" shows only a small "tip" to the public (e.g., 200,000 shares), but as soon as that tip is bought, the algorithm automatically reloads another 200,000 from the hidden "mountain" underneath until the full 2M is filled...
Off-Book / Negotiated Trades are the the truly massive chunks (e.g., 20M or 50M shares) are often negotiated directly between the Whale and a Market Maker (like MREX or SCAP) away from the public order book...
Under LSE rules, these large off-book trades don't have to be reported to the tape immediately. They can be delayed for several hours or until the end of the day. This is why you often see a "Late Print" surge at 4:35 PM...
At the current trading velocity, they only need to capture roughly 7.5% of the remaining afternoon volume to finish...