"The European Championship derails transfer activity," Fergie told Sky Sports.
"Nothing really happens during the tournament. But now it's all over, managers will be back at their clubs and you can get some dialogue now if there's interest.
"I wouldn't think we'll sign any more than one player. We are looking at one or two things.
"People think it's easy to buy players nowadays but it's not.
"Money plays a big part, first of all. And clubs with ambitions don't want to sell their best players.
"It's not as easy as you'd think. We tend to look for younger players."