McDonald’s Corp., which has thrived in recent years by emphasizing affordability and rolling out popular new menu items, is starting to show signs of tear from the volatile global economy.

The world’s biggest hamburger chain said Monday that its net income fell 4 percent in the second quarter as a result of the strong dollar and increasingly budget-conscious consumers. Suggesting more challenges ahead, the Oak Brook, Illinois-based company also said a key sales figure slowed in July.