What happened

Shares of Wisconsin temperature-controlled trucking operator Marten Transport (MRTN -3.31%) are red hot Tuesday afternoon, rising 15.3% as of 12:45 p.m. after beating second-quarter earnings estimates with a stick last night.

Expected to report a $0.32 per-share profit on sales of just $286.6 million, Marten wowed Wall Street instead with a report of $0.39 per share in profit and sales of $329.6 million.  

So what

Sales for fiscal Q2 surged 42% for Marten, and while about 10 percentage points of that came from fuel surcharges imposed by the company to offset "significantly higher fuel prices," the bulk of the growth was from stronger demand for the company's services, resulting in "the highest amount [of revenue] for any quarter in Marten's 77-year history," said management -- and at very strong profit margins to boot.  

Despite growing its staff of truck drivers by 15% over the course of the quarter, giving them raises, and "structurally improving our drivers' jobs and work-life balance," noted CEO Randolph Marten, the company managed to grow its operating profits 44% year over year (i.e., faster than sales growth) -- setting another all-time record for the company -- and grew its net profits 48%.

Now what

CEO Marten summed up the quarter in just five laconic words: "Consistent. Strong. Profitable. Organic Growth" -- to which I'd add a couple of words myself: "bargain-priced."

At $1.6 billion in market capitalization and with no net debt on its balance sheet at all, Marten stock looks admirably valued at less than 17 times trailing earnings, which seems very cheap for a stock that just posted 48% profits growth. And if Marten hits Wall Street forecasts for this year -- $1.41 per share -- the stock will look even cheaper in six months' time, at a current year price-to-earnings (P/E) ratio of 14.

Not bad, Marten. Not bad at all. Keep on truckin'.