Source: Union Pacific.

Shares of rail transportation operator Union Pacific (NYSE:UNP) fell as much as 1.8% in early Thursday trading after the company reported second-quarter results this morning. After a market-beating 22% gain year-to-date, simply meeting expectations wasn't enough to support the surging stock.

Operating revenue rose 10% year-over-year to $6.0 billion. GAAP earnings jumped 21% higher, stopping at $1.43 per diluted share. The results were exactly in line with analyst estimates.

The number of revenue-generating carloads increased 8% from the year-ago period. The remainder of Union Pacific's growth came from higher revenues per carload.

Five of Union Pacific's reportable divisions recorded low single-digit increases in average revenues per car, with the exception of a 4% decline in the automotive segment.

Agricultural freights led the way with a 19% annual revenue improvement, followed by 16% growth in intermodal and industrial revenues. Coal shipments took the cabooze position at the other end, growing by just 1%.

The company did not provide firm guidance for coming quarters or the full year, but CEO Jack Koraleski offered an "optimistic" view in prepared remarks.

"We are closely monitoring the economic landscape, along with the major drivers across all of our business segments, including the potential impact of weather on grain and coal," Koraleski said. "As the economy gradually continues to improve, the power of our diverse franchise provides business growth opportunities in all of our commodity groups."

Anders Bylund has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.