Costain Group PLC Stock: price and insider trades · United Kingdom

Costain Group PLC, founded in 1865, is a listed company based in Maidenhead, United Kingdom. Its directors and officers file their transactions with RNS (LSE). The last twelve months, up to 18 October 2026, brought 25 filings signed by 13 insiders.

Both sides are active: 7 purchases worth €90k and 9 sales worth €5.6M, from 5 insiders and 5 insiders respectively. Sales outweigh purchases by €5.5M. A purchase on the market is a deliberate choice to commit personal money, which is why it draws more attention than a grant. One trade stands out by size: a sale of €987k from Alice Mary Vaughan/alexander Vaughan, disclosed on 23 June 2026, or 0.14% of market capitalisation. The buyers include 3 board members and 2 senior executives.

The data flag 3 purchases as part of a group of insiders buying within 30 days of each other. Such overlaps are known as a cluster signal: distinct people reaching the same decision at about the same time. The most recent open-market purchase was published on 30 September 2026, 18 days ago. Typically, a trade is published a median of 1 day after it takes place. For comparison, UK MAR gives managers three business days to notify a trade. Keep in mind that insiders sell for many reasons unrelated to the outlook, from tax bills to estate planning.

For context, the typical company on the same exchange (median of 836 companies) published 6 filings over the same period, against 25 filings here. Looking back to 2023, when coverage begins, insiders filed 11 purchases and 12 sales.

Every figure here comes from the filings published by RNS (LSE) and describes the past, not future prices; it is not investment advice.