A €600 million trade in Ryanair shares was cancelled on Thursday when it emerged that the broker had been trying to buy Bank of Ireland stock.

A total of 47.8 million shares in the Irish airline, valued at just over €600 million, changed hands in London before the trade was cancelled.

It is understood that the broker involved was trying to buy 34 million Bank of Ireland shares, priced at about 19 cent each, as opposed to Ryanair equities, which had a €12.63 price tag.

The dealer labelled the order wrongly before putting it through, leading to the mix-up. The so-called “fat finger” error happened around lunchtime and the trade was cancelled shortly before 1.30pm.

Details of the cancelled trade showed up on the London Stock Exchange website and Bloomberg market news terminals while supervisors later confirmed what had happened.

Free float

Ryanair has a free float of 1.19 billion shares and 1.25 billion outstanding, 47.8 million equities would amount to 4 per cent of the company.

If a single buyer were to acquire that amount, stock exchange rules would oblige them to publish this information within two days.

Ryanair shareholders with more than 47.8 million shares include institutional backers Fidelity and HSBC and its chief executive, Michael O'Leary.

The incident had no impact on its shares, which ended the day in Dublin up 0.16 per cent at €12.70.