(Reuters) - U.S. burger chain Wendy's Co <WEN.O> said on Monday it would enter the Brazilian market in July through a joint venture that will open two restaurants in Sao Paulo.

"Brazil is one of the key global markets where we see considerable potential, and where we are investing additional energy and resources," Wendy's chief operations officer, Bob Wright, said in a statement.

The burger chain said in May it was experiencing a slowdown in sales in the current quarter, mainly due to a slump in demand in the United States, its biggest market.

The Brazilian fast food market was worth about $25 billion in 2015, according to research firm Euromonitor. McDonald's Corp <MCD.N> is the market leader, with an 8.7 percent share.

The move into Brazil, which is in its deepest recession in probably more than a century, comes ahead of the opening of the Olympics in Rio de Janeiro in August.

Wendy's Brazil is a partnership between Brazil's Infinity Services and the Starboard Group, one of Wendy's largest U.S. franchisees and a subsidiary of the fast-food company.

Wendy's and its franchisees operated 6,479 restaurants globally as of Jan. 3 in markets including Japan, Mexico and the United Arab Emirates.

The company's shares were down 3 percent at $9.36 early trading in a weak market. Up to Friday's close, Wendy's shares had fallen 10.3 percent this year.

(Reporting by Abhijith Ganapavaram in Bengaluru; Editing by Ted Kerr)