Artificial intelligence (AI) stocks have taken the stock market by storm. Chip-maker Nvidia is capturing a lot of attention for its technology, which drives many AI applications. But not everything in Nvidia-land is perfect, and in any case, Nvidia isn't the best option for every investor's wallet.

Investing legends Warren Buffett and Peter Lynch have both said they never invested in tech companies for a long time because they didn't understand them. Buffett mentions in his 1996 letter to Berkshire Hathaway shareholders that it's important to evaluate businesses within one's "circle of competence". In other words, you're better off investing in businesses you understand.

While Nvidia stock is up an unbelievable 190% so far in 2023, it's not the only high-gaining stock on the market. Carnival (CCL -1.34%) (CUK -1.34%) and Global-e Online (GLBE 0.59%) are both up more than 100% this year, and their bull run seems far from being over. In fact, these two stocks could even double from current prices.

1. Cruising is back

Carnival is one of 2023's outstanding stories, demonstrating an incredible comeback from the verge of dissolution. Its second-quarter results exceeded expectations, and the company is posting high sales growth, sky-high demand, and improving profitability. It's no surprise that its price is up nearly 140% this year.

The major detraction from buying Carnival stock is its debt. It was forced to issue massive debt to stay alive when cruises were shut down, and while that was successful, it's now stuck with paying back cruise-loads of debt, and it will be saddled with this for a long time. This puts it in a fragile situation if anything else goes wrong. Management is on top of addressing this, and it knows it's a top shareholder concern. It has outlined a clear plan for paying off the debt, but there's no way to guarantee that it will all go as planned over several decades.

There are many top companies that carry enormous debt loads, but investors aren't worried about them. Consider McDonalds, which has $36 billion in long-term debt, and Home Depot, which has more debt than Carnival. But they also demonstrate high and reliable profits and cash flow, which are more than ample to manage the debt load and fund the dividend. That's a certain model.

CCL Free Cash Flow Chart
CCL Free Cash Flow data by YCharts.

Carnival's debt looks dangerous because the company isn't net profitable and is just starting to turn a corner on positive cash flow. Based on current reservation levels and expected demand over the next few quarters, the potential to get back to profits is a definite reality, which is why investors are becoming enthusiastic about Carnival stock.

Management has been able to raise prices while demand is at record highs -- bookings and deposits were both at all-time highs in the 2023 second fiscal quarter (ended May 31), and revenue of $4.9 billion was a record for a second quarter. Bookings exceeded the previous record in the first quarter, and the acceleration has continued into the third quarter. So momentum and expectations are high.

At the current price, Carnival has a market cap of nearly $25 billion. If it doubles again, it will reach $50 billion. To make that happen at the current price and trailing-12-month revenue levels, its price-to-sales ratio would double to 2.7, which is still quite low. However, by the end of the year, trailing 12-month revenue should increase as compared to where it is today based on higher revenues now year over year and expected increases based on record bookings. At a doubled price, that implies a higher sales figure at a price-to-sales ratio that might increase, but not double. And even after doubling in stock price, Carnival could still be reasonably priced.

2. It's a small world after all

Global-e is another incredible company whose stock is up 110% this year. Global-e is a fairly small and lesser-known company, with only $450 million in trailing-12-month revenue. It's only been public since the end of 2021, and it's posted high double-digit sales growth every quarter since. This is the classic stock opportunity to buy early and get the most out of your investment. It's also the classic unprofitable growth stock, which is why there's a certain level of risk involved in this investment.

The reason it looks compelling, regardless of the risks, is because the business model seems solid, and profitability is improving. In the first quarter of 2023, adjusted earnings before interest, taxes, depreciation, and amortization (EBITDA) improved to $14.5 million this year versus $3.3 million in the year-ago quarter, and net loss narrowed to $43 million from $53 million over the same time frame. Global-e has a path to profits in the near future as it scales.

The company sells cross-border e-commerce solutions to retailers, and it deals with businesses of all sizes, from small businesses to top companies like Neiman Marcus and Marks and Spencer. It recently inked deals with brand-conscious names like Kylie Cosmetics and Katy Perry, and it also keeps expanding current partnerships with high-name-recognition companies like Disney.

For the stock to double again, it would rise from about $7 billion in market cap to $14 billion. At a price-to-sales ratio of 15, it would become unreasonably expensive to double at the current revenue levels. But trailing-12-month revenue should be much higher by the end of the year than it is now; management guided 2023 revenue to increase by a solid 44% from 2022, with $590 million at the high end of guidance. At a market cap of $14 billion, that would indicate a price-to-sales ratio of more than 23. That's already very expensive, even for a high-growth company like Global-e. Can it get there? It's less likely than Carnival, but it's possible. It's also possible that as Global-e adds partners, and if the economy improves, sales growth will exceed guidance.

In any case, there's a strong premise to say Global-e stock could double again, and if not by the end of the year, then not too long after.