What happened

The cost of shipping oil around the world is on the rise this week, and if you think that might be good news for oil tanker stocks, you're right!

As of 3:20 p.m. EST Wednesday, shares of Nordic American Tankers (NAT -1.87%) are up a strong 8%, Teekay Tankers (TNK 0.08%) is up 10.5%, and Scorpio Tankers (STNG -0.54%) is up 11.4%.

Stock chart shows a red line going down in 2020 and going back up in 2021

Image source: Getty Images.

So what

Not all "tankers" are created equal, of course. Nordic American focuses its efforts on the transportation of crude oil, while Scorpio transports primarily refined petroleum products, and Teekay does both. The good news for these stocks, though, is that no matter what they transport, the prices they can charge for transportation are going up.  

According to the latest data out of Lloyd's List, after a slump that began in January, both the "clean" (refined petroleum) and "dirty" (crude oil) indexes have been rising over the past several days. From a 2021 low of 478, the Baltic Clean Tanker Index (BCTI) was up 5.2% yesterday, and the Baltic Dirty Tanker Index (BCDI) was up 4%.  

Now what

All three stocks are up much more than 4% or 5% today, of course, and that may seem disproportionate to the gains racked up in the indexes -- especially given the tenuous state of the companies' balance sheets. Nordic American, for example, is carrying more than $350 million in debt on a market capitalization of just $480 million, while both Teekay and Scorpio carry debt levels considerably higher than their respective market caps.

Investors, though, I suspect, are betting that the gains we've seen over the past week are just the beginning of a resumption of the longer-term trend of rising prices for oil transport that began last summer. If they're right about that, then the gains oil shipping stock investors are enjoying today could be just the start of the good news.