Recent market declines mean some solid biotech companies are on sale. And that means it's time for biotech investors to start shopping. You don't have to restrict your search only to stocks that have declined in the past few days though.

You'll also find great quality stocks that have been lagging behind since the start of the year. While some names have surged, biotech as a whole hasn't been the most profitable investment these past few months. The iShares Nasdaq Biotechnology ETF has slipped about 1% since the start of the year. That's while the S&P 500 gained more than 11%. Now, let's use this opportunity to stock up on shares that will deliver over the years to come.

An investor sitting in his office smiles as he looks at his investments on his cell phone.

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Vertex

Vertex Pharmaceuticals (NASDAQ:VRTX) is the leader in the cystic fibrosis (CF) market. This generates billions in annual revenue for the company. In fact, annual revenue has been rising for the past six years and totaled more than $6 billion last year. And profit has climbed for most of the past six years.

Even better, the company launched a new CF treatment in late 2019 -- and it has the potential to treat about 90% of CF patients. The treatment -- Trikafta -- generated $3.9 billion in its first full year of commercialization. Vertex expects to increase sales through the expansion of use across age groups and geographies.

Though Vertex says it will remain the CF leader through the late 2030s, investors want more. They want the company to broaden work into other treatment areas. Vertex is doing this -- and programs such as gene editing therapy in blood disorders are showing promising results in clinical trials.

Vertex shares are down about 8% so far this year. And the stock is trading at less than 20 times forward earnings. That's down from more than 29 back in July. Considering Vertex's CF market position and future prospects, the shares are a bargain at this level.

Seagen

Seagen (NASDAQ:SGEN) is just beginning its growth story. The biotech was a one-product company in late 2019. It commercialized a treatment for Hodgkin lymphoma. Since then, the U.S. Food and Drug Administration (FDA) approved two more of Seagen's product candidates -- Padcev for the most common form of bladder cancer and Tukysa for breast cancer.

All of this means a sharp increase in revenue. The company's product sales climbed nearly 60% year over year to $1 billion last year. And product sales in the first quarter of this year rose more than 50% to $302.6 million. The company forecasts product revenue of as much as $1.3 billion for 2021.

Seagen also aims to benefit from expanded indications for its commercialized products. The FDA is considering Padcev for use in additional bladder cancer patients. A decision is set for Aug. 17. Seagen's pipeline includes at least seven potential indications for each of its three commercialized drugs. And the company is studying about 10 other candidates for various indications too.

Seagen shares have slipped 15% this year. And right now, the stock is trading at only 11 times sales. That's close to its lowest over the past 10 years.

Moderna

Moderna (NASDAQ:MRNA) might not seem like a huge bargain. The stock is up about 50% so far this year after all. But the past couple of weeks offer an opportunity to get in on this exciting player in the coronavirus vaccine market. The stock has slipped 10% since the start of the month.

As we've seen over the past months, windows of opportunity to buy Moderna shares happen -- but the stock quickly rebounds and extends earlier gains.

MRNA Chart

MRNA data by YCharts

And for good reason. Moderna is one of the two leaders in the coronavirus vaccine market. The company reported its first profit in the most recent quarter. And that's only a few months after launching the vaccine.

Moderna expects $19.2 billion in revenue from the vaccine this year. And that may be just the beginning. In the earnings call earlier this month, the company said market need for next year is looking even stronger than need this year. Experts say the coronavirus will stick around well into the future too. That means Moderna's vaccine revenue likely will be recurrent.

Beyond the vaccine, Moderna has other revenue opportunities on the horizon thanks to a full pipeline. Closest to market is its cytomegalovirus (CMV) candidate. It's set to begin phase 3 trials this year. CMV is a common virus that may be dangerous for those who are pregnant or have weakened immune systems.

All of these elements equal plenty of catalysts to power Moderna shares higher in the long term.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.