Neither company put out a regulatory announcement of an agreement or of an end to discussions: The Guardian (5 August) reported that shareholders had been told nothing, The Times (5 August) carried a senior-source denial that the talks were live, and AstraZeneca's own August press releases were clinical only.
The market resolves on a regulatory news release from either company on the RNS at londonstockexchange.com by 23:59 BST on 1 September 2026, either announcing a firm merger agreement or offer, or formally stating that discussions have ended. A holding statement that merely confirms talks are ongoing resolves nothing and the market stays open. If that source has not published in time, astrazeneca.com or investegate.co.uk, and SEC EDGAR for Bristol Myers Squibb settle it.
We looked for merger talks involving a UK-listed drugmaker that became public before any deal was signed. Since 1998 this has happened five times. All five ended within six weeks, either with a firm offer or with the talks dead. Two produced an agreed or firm offer, and three collapsed.