I was a little late to the party in buying Guardant Health (GH -4.30%). After watching the stock soar during the latter part of 2018 and the first half of 2019, I finally jumped in to scoop up shares in July of last year. I'm glad I did.

But do I regret missing out on investing in Guardant Health at its initial public offering (IPO)? Yep. If you didn't get in on the IPO, you might already share the same regret (at the very least, you soon will). Here's how much you'd have today if you had invested $10,000 in Guardant Health's IPO.

Five increasingly higher stacks of coins with blocks spelling out IPO on the three highest stacks and a businessman holding a red line trending up in the background

Image source: Getty Images.

A huge winner

Some IPO stocks rise quickly but then the gains evaporate. Not Guardant Health. It's been a huge winner since day one.

Guardant Health operated as a privately held company for roughly six years before listing its shares on the Nasdaq stock exchange in October 2018. It priced the IPO at $19 per share. That would turn out to be the cheapest level at which anyone would be able to buy the stock going forward.

On the market open on Oct. 4, 2018, Guardant Health's shares traded at a 46% premium to the IPO price. The stock closed its first day of trading up a whopping 68% above its IPO level. Then came a roller-coaster ride -- but one that ended up being a great one for investors.

GH Chart

GH data by YCharts

A $10,000 investment in Guardant Health's IPO would have allowed you to pick up 526 shares (and have a little money left over). If you had held onto those shares, you'd now have a little over $58,800. That's a 488% return in less than two years. 

Behind the success

What did Guardant Health do to achieve such tremendous success? The company didn't need any smoke and mirrors. It simply delivered the kind of results that investors love.

Demand for Guardant Health's liquid biopsy products has been fantastic. The company currently markets two products. Guardant360 helps determine the best therapy for patients with advanced-stage cancer to take. GuardantOMNI helps biotechs and pharmaceutical companies screen patients for clinical studies of experimental cancer drugs.

Guardant Health's momentum really began to pick up in February 2019. That's when the company announced great results from a study comparing Guardant360 against standard-of care tissue testing in detecting key biomarkers used in identifying advanced non-small cell lung cancer. 

There were some pullbacks along the way. For example, Guardant Health's shares plunged earlier this year when the stock market tanked during the early days of the COVID-19 pandemic. But the company has had a lot more good news than bad news. Most recently, Guardant Health won FDA emergency use authorization in August for its next-generation sequencing-based COVID-19 test.

Still in its early stages

Could Guardant Health more than quintuple an initial investment of $10,000 over the next few years? It's possible.

The company is definitely still in its early stages. Guardant Health estimates that the annual market for Guardant360 is around $6 billion in the U.S. alone. It's on track to generate around $270 million in total revenue this year. 

However, the opportunity for Guardant360 pales in comparison to what the company's liquid biopsy products on the way could have. Guardant Health is currently testing its LUNAR products in clinical trials. LUNAR-1 holds the potential to detect cancer recurrence and assist drugmakers in developing adjuvant therapies for early stage cancer. LUNAR-2 targets detecting multiple types of cancer at early stages. The company thinks that the two products combined have an addressable U.S. market of over $45 billion per year. 

Granted, Guardant Health will have intense competition going after these markets. Gene-sequencing giant Illumina plans to fully acquire its former spinoff GRAIL, which is developing a promising liquid biopsy product. Exact Sciences and Foundation Medicine, which is now owned by Roche (RHHBY 0.87%), are other formidable rivals. 

But don't discount Guardant Health's chances of success. You just might regret it if you do.