LONDON — NYSE Euronext agreed on Tuesday to buy a 25 percent stake in the Qatar securities market, gaining a lead in the race against its British and German rivals to become a truly global stock exchange at a time when growth has slowed in their home markets.

NYSE, which is based in New York and owns several European exchanges, will pay $250 million in cash for the stake in the Doha Securities Market and gain a foothold in the fast-growing Middle Eastern economy. NYSE Euronext beat the London Stock Exchange, which counts Qatar’s investment authority among its shareholders, and Deutsche Börse in a six-month takeover competition.

“There is no doubt that in the medium to long term, the Middle Eastern markets will grow faster than the West, and the idea to buy into it is a good one, but it also has to make economical sense,” said Colin Morton, a fund manager at Rensburg Fund Management in Leeds, England.

NYSE shares rose 60 cents, to $56.72.

Stock markets are combining or buying stakes in one another to meet clients’ demands to trade shares anywhere and at a faster pace. The recent turmoil in the credit markets increased the pressure to look for growth in less-developed markets as trading in many of the more established markets slowed and fewer companies sold shares in initial public offerings.

NYSE announced in January that it would pay $115 million for 5 percent in the National Stock Exchange in India, and Dubai ended up with minority stakes in Nasdaq OMX and the London exchange as part of the takeover battle.