U.S. factory orders rose by 2.1 percent in May, the Commerce Department said Tuesday. The rise of $9.9 billion, which was more than analysts were expecting, means that orders have been up for three of the last four months.

The consensus among Wall Street analysts was that factory orders would go up by 1.9 percent or 2 percent for May following April's revised gain of 1.3 percent. Excluding transportation, new orders increased 0.6 percent.

Orders for factory equipment were particularly strong in May, the Commerce Department said.

The indicator measures the change in the total value of new purchase orders placed with manufacturers and is considered a leading indicator of production since rising purchase orders signal that manufacturers will increase activity as they work to fill the orders.