What happened

Cruise line stocks are dropping across the board in Thursday-afternoon trading -- and that just isn't fair.

As of 12:35 p.m. EDT, shares of Royal Caribbean (NYSE:RCL) have tumbled 5.2%, Norwegian Cruise Line Holdings (NASDAQ:NCLH) is down 4.2%, and even industry giant Carnival (NYSE:CCL) (NYSE:CUK) is slipping 2.5%. Furthermore, all three of these cruise stocks were down more than 5% in trading earlier in the day.

And yet the news isn't all bad.

Chart of new COVID-19 cases dated July  9, 2020.

New COVID-19 cases reported daily through July 9, 2020. Image source: Our World In Data, a project of the Global Change Data Lab 2020. Licensed under CC BY. Chart Copyright Our World In Data, a project of the Global Change Data Lab 2020.

So what

Wednesday, as you may recall, representatives from cruise lines Royal Caribbean and Norwegian Cruise joined forces to form a Healthy Sail Panel taskforce to work out procedures to ensure passenger safety if and when cruise lines are permitted to resume sailing later this year. Not long after this was announced, moreover, it was revealed that the independent auditor in charge of reviewing Norwegian's books found the company's financial position sufficiently improved that it removed a comment expressing "substantial doubt about NCLH's ability to continue as a going concern."

Granted, that's something of a double negative. But what it means, in effect, is that in the current opinion of its auditor, Norwegian Cruise Line Holdings will not go under, will not succumb to the coronavirus pandemic, and will survive to emerge on the other side of this recession healthy enough to remain in business.

Moreover, this morning, Carnival subsidiary AIDA Cruises announced that it plans to resume cruising in August -- ahead of the Sept. 15 U.S. restart date previously promised by most cruise lines. Three of AIDA's vessels plan to resume cruising from ports in Germany, each operating under "a comprehensive set of health and hygiene protocols to help facilitate a safe, healthy and phased-in return to cruise vacations." They're sailing with an "adjusted passenger capacity," to be sure, and "without calling at another port" -- but they're sailing, and that has to be good news for Carnival's revenue stream.

Analysts at Wells Fargo promptly more than doubled their price target on Carnival stock to $12 a share.

Now what

So why are cruise stock prices going down today instead of up? Partly, I suspect, this is an effect of the negative macroeconomic news we got today: 33 million Americans are still out of work and unlikely to have the discretionary income to spend on a cruise until they find new jobs. And daily new cases of coronavirus infection continue to edge up both in the U.S. and globally, and the World Health Organization warns that the pandemic is definitely "not under control" just yet.

And partly, it's an effect of cruise stocks being stocks, period, and thus susceptible to being dragged down when stock market sentiment sours -- as it's doing today, with the S&P 500 down as much as 1%.

It's a shame, and it's not fair, seeing as today's cruise news is actually pretty good. But then again, no one ever promised that the stock market would treat you fairly.