C.H. Robinson Worldwide executives knew the second half of the year would be tough, but it started out worse than they thought.

Shares in the Eden Prairie-based logistics and shipping company plunged 15% Wednesday as investors soaked in bigger-than-expected profit and sales declines during the July-through-September quarter.

The trucking industry, after years of growth constrained only by limits on number of drivers, has swung into having too much capacity. Meanwhile, air and sea cargo shipping is being hurt by the global trade war. Shipping prices have fallen sharply as a result, eroding sales and profits at C.H. Robinson.

"We anticipated an aggressive industry pricing environment coming into the second half of the year, driven by excess capacity and softening demand," Bob Biesterfeld, the company's chief executive, told analysts Wednesday.

But he said pricing for truck hauling fell faster than costs for the first time since early last year. The company's single-digit increases in its contractual truckload volume was offset by significant declines in spot-market pricing. Employees "did a great job of controlling what we can control, which includes winning increased awards in contractual bids" as the pendulum swung in the trucking industry, Biesterfeld said.

"We're not immune to large cyclical swings in the freight environment," he said. "We believe that our continued investments through these downcycles will drive better alignment between our net revenue growth and our costs."

Even so, executives expect per-shipment trucking revenue to be below year-ago levels for the next three quarters, into the middle of next year. Contract pricing is also likely to remain flat through the rest of this year and into the start of 2020.

"Forward trends look to remain quite weak," Jordan Alliger, an analyst at Goldman Sachs who follows the company, wrote after the results were announced.

C.H. Robinson said its profit fell 17% to $146.9 million against a strong third quarter last year. That amounted to $1.07 a share, below the $1.14 a share that was the consensus estimate of analysts who cover the company.

Revenue was $633.4 million, down 9%. Operating income was $201.1 million, down 18%.

In the company's largest segment, North American surface transportation, revenue fell 13% and operating income was down 21%.

Biesterfeld told analysts that declines in the company's air and ocean shipping volumes were tied to trade tariffs and fears of slowing global economic growth.