U.S. factory activity unexpectedly rebounded in January after contracting for five straight months amid a surge in new orders, offering hope that a prolonged slump in business investment has probably bottomed out.

A rebound in business investment is critical to keeping the longest economic expansion in history, now in its 11th year, on track amid signs of fatigue in consumer spending. The economy grew 2.3 percent in 2019, the slowest performance in three years, after expanding 2.9 percent in 2018.

The Institute for Supply Management (ISM) said on Monday its index of national factory activity increased to a reading of 50.9 last month, the highest level since July, from an upwardly revised 47.8 in December.