Ranked by market value (market capitalisation) as of September 2026. A company counts for the country it is legally based in. Values are approximate, in US dollars.
#1
? ? ?Data storage · $192B
#2
? ? ?Power management · $160B
#3
? ? ?Medical devices · $120B
#4
? ? ?Consulting · $114B
#5
? ? ?Air conditioning · $99B
#6
? ? ?Building technology · $88B
#7
? ? ?Building materials · $63B
#8
? ? ?Credit data · $33B
#9
? ? ?Industrial machinery · $30B
#10
? ? ?Airline · $29B
Rules & what counts
Biggest Companies in Ireland Quiz — Rules & What Counts
This quiz shows 10 cards, ranked from 1 to 10. Each card is one of the 10 biggest companies in Ireland, by market value. Type a company name to reveal its card.
Each card shows its rank, the sector of the company and the value of the company. The logo appears when you name the company.
Market value is the total value of a company's shares on the stock market. The values are approximate and in US dollars. They change every day, and the board updates from time to time.
How to play
Just start typing. The quiz checks your answer at every keystroke. There is no submit button.
A correct name reveals the card at its rank, with the company's logo and full name.
You can answer in any order. The name you type reveals the matching card wherever it sits.
Everyday names count. Short names, initialisms and old names of the same company are accepted.
Spelling is forgiving. Capitals, accents and punctuation are ignored.
The timer starts at your first keystroke and counts up. Give Up ends the run and shows every company you missed. Progress saves automatically.
What counts in this quiz
The 10 companies with the highest market value that are legally based in Ireland.
A company counts for the country it is legally based in, not for the country of its founders or its factories.
Operating subsidiaries with their own stock listing count as their own company.
What's not included — and why
Companies outside the top 10 do not count. A guess that is not on the board changes nothing. There is no penalty.
Holding companies whose only value is a stake in another company on the board are left out.
Companies that are not listed on a stock exchange have no market value, so they are not on this board.
Good to know
Seagate is the biggest company in Ireland, worth about $192B. It is a data storage company.
The tenth company on the board, Ryanair, is worth about $29B.