AstraZeneca shares rose following reports that there had been ‘no discussions’ about a potential mega-merger with a US rival.

The pharma giant’s stock climbed 2.5 per cent, or 296p, to 12,036p after Reuters quoted a senior source dismissing rumours of a potential tie-up with Bristol Myers Squibb (BMS).

The source said: ‘There is no deal between ​AstraZeneca and BMS. There never was a deal to be ​done, and there are no discussions between the companies.’

The report cited another source who said there were no active talks between the firms. 

BMS shares fell 3 per cent on Wall Street.

Some £18billion was wiped off AstraZeneca’s market value on Monday as analysts and investors questioned the rationale behind the rumoured merger.