Union Pacific reported a fourth-quarter profit on Thursday that rose 7% on the back of higher grain and fertilizer shipments and core pricing gains, sending the railroad operator's shares up more than 4% before the bell.

The company, seen as a bellwether for the U.S. economy, has benefited from improving revenue in its grain, chemicals and intermodal segments following higher West Coast imports and a strong harvest season.

In December, Union Pacific executives said they were starting to see improvements in domestic intermodal shipments, driven by volumes coming through West Coast ports.

Disruptions in the Red Sea, coupled with threats of potential new tariffs and a labor dispute at seaports on the U.S. East and Gulf Coast saw import volumes rising particularly on the West Coast.

However, Union Pacific's operating revenue of $6.12 billion in the fourth quarter missed the average analyst estimate of $6.14 billion, according to data compiled by LSEG.

The Omaha, Nebraska-based company reported an operating ratio of 58.7% for the quarter, an improvement from 60.9% a year earlier.

A higher operating ratio reflects an increase in costs, suggesting lower profitability.

Union Pacific posted a net income of $1.76 billion, or $2.91 per share, in the fourth quarter, compared with $1.65 billion, or $2.71 per share, a year earlier.