Moderna (MRNA 1.69%) was one of the hottest stocks to own during the rollout of COVID-19 vaccines a few years ago. These days, however, the hype has cooled off significantly. The company is facing big questions about its future growth, and there isn't a whole lot of bullishness surrounding the stock anymore. The stock dropped nearly 45% in 2023.

Moderna investors might be looking back and pondering how things have gone. Let's take a look at how much an investor would have today if they invested $10,000 into the stock before the pandemic.

Where Moderna's business was before the pandemic

At the end of 2019, Moderna was a high-risk business to invest in, having accumulated a deficit of $1.5 billion since its inception in 2009.

At the time, the company was generating revenue primarily from collaborations and grants. But at $60 million for 2019, it was nowhere near enough to cover the company's operating expenses, which totaled $606 million that year. Although the company had 20+ programs in its pipeline in development as of the end of the year, there was plenty of uncertainty surrounding the business.

The stock's value as of the end of 2019 was just over $19

Moderna's stock closed 2019 at $19.56. That was about two weeks after a group of patients in Wuhan, China, began to experience symptoms of a pneumonia-like illness.

If you had invested $10,000 in the healthcare stock on the last day of 2019, you would have acquired approximately 525 shares of the company. The stock would go on to soar to highs of more than $400 in 2021 before coming crashing down in recent years.

Today, it trades around $100 and those 525 shares would be worth approximately $52,500. Even with the stock's 45% decline last year, investors who had hung on would still be well ahead of where they were four years ago. By comparison, a similar-sized investment in the S&P 500 would be worth roughly $16,000 right now.

Moderna benefited greatly from sales of its COVID-19 vaccine. It began the first human trials of a COVID-19 vaccine in March 2020, and the FDA issued an Emergency Use Authorization for a Moderna vaccine in December of that year. In 2021, Moderna stock rose 143%.

Moderna's future is back to looking uncertain

Although Moderna's management is optimistic about the future, investors are right to have more than just a healthy dose of skepticism. This year is one of transition, with Moderna projecting that its total revenue will come in at just $4 billion -- nowhere near the $19 billion it reported for 2022. It does expect to generate organic growth next year, and by 2026 it expects to hit breakeven.

That's an ambitious target for Moderna given that over the first nine months of 2023, its net loss was $4.9 billion -- more than the $4 billion in revenue it generated. The company will have to adjust its operations so they are leaner, but at the same time it will also need growth catalysts for the top line. The company has multiple products it is working on, including a COVID-19 and flu combination vaccine, a vaccine for the respiratory syncytial virus, and a cancer vaccine it has been developing with Merck.

But as of now, there isn't a surefire thing that will lead Moderna back to generating strong growth, much less profitability anytime soon. Its pipeline had many programs in 2019 (including multiple personalized cancer vaccines) and in the end it was the unexpected COVID-19 vaccine that proved to be the game changer for the business.

Investors should be careful not to assume that having many assets will lead to future revenue growth and a safer business in the long run.

Is Moderna worth investing in today?

It's tempting to think of Moderna's share price as being cheap given the highs it achieved in 2021. But it's hard to accurately value this business given all the moving parts, including which products will obtain approval, how much in costs it can trim, and what the demand for COVID-19 vaccines will look like in the future.

At $40 billion, Moderna's market cap is by no means cheap, not for a business that may only generate $4 billion in revenue this year. For investors, the safest approach is to wait on the sidelines and see how the company does. This could prove to be a volatile stock for the foreseeable future.