A lot of stocks have been rallying lately, but not all of them have earned their upticks. Among the 100 most widely held stocks among Robinhood traders, I think Norwegian Cruise Line Holdings (NCLH 1.24%) and American Airlines Group (AAL -0.35%) are pretty vulnerable right now.

I hope I'm wrong, but sometimes the market's enthusiasm doesn't match the fundamentals. Let's see why I think these two hot stocks could cool off in June.

A woman wearing snorkel gear and a face mask makes an X with her arms.

Image source: Getty Images.

1. Norwegian Cruise Line

These are exciting times for the cruising industry. After a 15-month drought the largest cruise lines will initiate test sailings this summer, clearing the way for the resumption of revenue-generating voyages if they can clear the regulatory hurdles. 

Investors have been bidding up the cruise lines in anticipation of the start of the turnaround process, but what if the stocks have outrun their fundamentals? A quick look at Norwegian Cruise Line's stock shows that at Wednesday's close of $33.07 the stock is within pocket change of the 52-week highs it set in March, but a little more than half of where it was three years ago when the shares briefly traded above $60 apiece. 

The long-term chart makes sense. It's going to take time before Norwegian Cruise Line gets back to where it was when its fiscal performance peaked in 2018 on the bottom line and 2019 on the top line. Cruises won't be as profitable as they were for some time given the new protocols and the need to convince consumers that it's safe to go cruising after so many COVID-19 casualties took place on the floating vessels. 

Unfortunately for Norwegian Cruise Line investors the stock chart is an optical illusion. Norwegian Cruise Line has had to issue a ton of stock and gobs of debt to stay afloat during the past year-plus of downtime. Its enterprise value -- the stock's market cap plus its debt minus its cash and equivalents -- has ballooned dramatically with every new stock or bond transaction. This is true of all three major cruise lines, but as the smallest of the three Norwegian is the one that is most susceptible to failure in these uncharted recovery waters.

Over the past five years Norwegian Cruise Line's enterprise value has been as low as $8 billion and as high as $21 billion. It just closed at an enterprise value above $21 billion for the first time on Wednesday. In short, the value of the cruise line that still has a long way to go to get back to where it used to be has never been as high as it is right now. Even optimists concede that it will take a couple of years for Norwegian Cruise Line to get back to where it was in terms of revenue and even longer when it comes to earnings. 

2. American Airlines

There are three airline stocks among Robinhood's 100 top investments. American Airlines just happens to be the only one that analysts don't see turning an annual profit until 2023. The legacy carrier has a clearer path to recovery than Norwegian Cruise Line. It didn't have to ground its fleet of planes for 15 months the way that the cruise lines have, and we're seeing airport foot traffic start to recover. 

My beef here is that there are two parts to the recovery of the airline industry. Consumers are starting to come back, and having shelved away their savings for their 2021 vacations you know that the recovery will be strong for domestic travel this summer and beyond. It will take longer for the more lucrative international routes to recover given worldwide travel restrictions, but at least we're seeing the trend in general improving.

Corporate travel is where I think American Airlines, and most air carriers in general, will struggle. We're not seeing a rush for business trips to visit clients or participate in conferences. We've embraced videoconferencing as an acceptable way to get things done. Nothing beats a warm handshake and a cold drink to close business deals, but corporate travel was always a costly and time-consuming endeavor. It's not going to go away completely, of course. However, it will be hard for a lucrative segment for legacy carriers -- so important that there's even a business class tier of premium-priced seating -- to make a full recovery in the coming years. 

With American Airlines posting a larger-than-expected loss in its latest quarter and analysts revising their profit targets for the worse in recent months it is hard to get excited about the iconic air carrier. We've seen travel and tourism stocks bounce back, but it's hard to see the businesses themselves in some cases following suit anytime soon.