What happened 

Shares of Knight-Swift Transportation Holdings Inc(NYSE:KNX) fell as much as 19% in trading Thursday after reporting second-quarter earnings. At 12:55 p.m. EDT, shares were down 11.3% on the day. 

So what

Revenue was up 387% to $1.33 billion for the quarter, and net income jumped 408% to $91.3 million, or $0.56 per share on an adjusted basis. The huge growth numbers were driven by the Knight and Swift merger in the third quarter of 2017. 

Truck driving on highway.

Image source: Getty Images.

The disappointment wasn't from the revenue number, which matched analyst estimates. But earnings fell a penny short of estimates, and that's why we see shares falling today. The hope was that higher demand and synergies from the merger would push earnings higher, but that didn't come to fruition today. 

Now what

The trucking business has been helped by rising demand and prices as the economy grows. But investors had higher expectations for Knight-Swift now that it holds the title of "largest truckload transportation company" in North America. I wouldn't be too worried about a small miss on earnings, and I think this is a company set up to profit from more economic activity long term.