Even with oil rallying and WTI pushing back toward $50, no one is predicting a sharp return to last summer’s $100 oil prices. While some of the effects of cheap oil are obvious, it can be tough to identify all of the secondary effects and the conflicting impacts they can have on any given sector.

Oil fluctuations impact a large number of industries in a variety of ways, making it easy for misconceptions to form,” says a Cowen and Company research paper released earlier today. “We strive to set the facts straight by articulating, for instance, why many trucking companies do not benefit from a decline in the price of diesel fuel.”

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LTL carriers could take a hit despite cheaper fuel

Even though there is a delay between falling crude and diesel prices, intuitively the change should eventually benefit trucking companies by pulling their costs down, but this isn’t the whole picture. Cowen analysts Jason Seidl and Matthew Elkott point out that many trucking companies hedge against changes in fuel prices so not everyone gets the same benefit from lower prices. Knight Transportation is much more sensitive to diesel prices than JB Hunt Transport Services, for example.

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Cheaper diesel isn’t even necessarily a good thing for less-than-truckload (LTL) carriers, who typically benefit from rising prices because higher surcharges more than make up for higher costs. You would expect rail to be the big loser in the industry because it both becomes less competitive against TL carriers and loses revenue as crude shipments fall off, but Seidl and Elkott say that rail companies have become a lot more flexible in recent years and can scale down more quickly than investors might expect. That doesn’t mean they will benefit from cheap oil, but investors may be overestimating its impact.

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AA is Cowen’s top airlines pick

“The airlines collectively benefit from lower fuel prices, but those with the biggest positive surprises are American Airlines and Allegiant Travel, neither of which hedge jet fuel,” explains Cowen analyst Helane Becker.

Even though the airline industry will spend a lot less on fuel this year, Becker forecasts that Delta Air Lines will post a $2 billion hedge-related loss in 4Q14 alone, while Southwest Airlines will lose $0.5 billion and United will lose $0.2 billion.

American Airlines is Becker’s top pick because it will get maximum benefit from cheap jet fuel and has a young fleet – the 100 planes it got in 2014 are more fuel efficient and won’t require serious maintenance for a couple of years, pulling down operating costs. America Airlines will also complete its merger with US Airways this year, and despite the positive spin that Becker gives it there is some reason for concern.

“The management team has experience in merging airlines, and given how poorly the US Airways/ America West merger went, we are hopeful they know the pitfalls and will avoid them,” Becker writes.