You don't have to start out with thousands of dollars to grow your wealth in the stock market. In fact, with just $100, you can buy shares of companies that can boost your portfolio over time. Plenty of healthcare players offer you this opportunity right now.

Let's talk about two biotech companies that are just beginning their growth story -- and a big pharmaceutical company that's about to embark on a whole new wave of growth. With $100, you can get in on at least one of these players right now. Read on for a close look at each.

1. CRISPR Therapeutics

CRISPR Therapeutics (CRSP -1.24%) is a specialist in the exciting area of gene editing. The company doesn't have a product on the market yet. But that may change soon. CRISPR and partner Vertex Pharmaceuticals recently completed regulatory requests for exa-cel -- a treatment candidate for blood disorders -- in the U.S., the U.K., and Europe.

Exa-cel is designed as a one-time curative treatment for sickle cell disease and beta thalassemia. This could be big because these disorders have limited treatment options today and leave patients facing a lifetime of hospitalizations.

CRISPR's gene-editing technology doesn't stop with exa-cel. The company's immuno-oncology candidate, CTX110, is in a phase 2 trial that may support a regulatory request. So, if all goes well, CRISPR could bring two products to market in the not-too-distant future.

The biotech has other candidates in the pipeline and has licensed its gene-editing technology to Vertex for use in the company's type 1 diabetes program. All of this represents potential revenue sources for CRISPR down the road and drivers of share performance.

2. Axsome Therapeutics

Axsome Therapeutics (AXSM 0.81%) launched its first two products last year. First, it rolled out sleep disorder drug Sunosi, which it acquired from Jazz Pharmaceuticals. Then it won approval for antidepressant Auvelity. Both drugs potentially could bring in revenue of more than $1 billion according to analyst and company estimates.

Axsome's pipeline includes other interesting candidates, and all of them are at least in phase 2 development. This is positive because it could lead to other commercialized products in the coming few years. For instance, Axsome recently reported solid data in a phase 3 trial for its candidate for Alzheimer's disease agitation. There currently aren't any commercialized treatments for this problem, so it could be a big opportunity for Axsome.

The biotech also aims to resubmit its migraine candidate to regulators this year after addressing questions about chemistry, manufacturing, and controls.

The stock beat the bear market last year. But this year, Axsome shares have declined 11%. This offers a terrific buying opportunity for investors who aim to buy now and hold for the long term.

3. Pfizer

Some investors have worried about Pfizer (PFE -0.23%) for two reasons. The company, like other COVID-19 vaccine makers, is facing a drop in demand. The big pharma company also is set to lose exclusivity for older blockbusters later this decade.

But Pfizer has prepared for this moment. The company acknowledges that coronavirus vaccine demand is falling but still expects its coronavirus portfolio to bring in blockbuster revenue for the foreseeable future. That's because the coronavirus will stick around in a post-pandemic world. And people still will need Pfizer's vaccine/booster and treatment.

The company also has beefed up its pipeline. In fact, it announced a record number of potential products -- 19 -- to hit the market over the coming 18 months. Pfizer expects these products to add $20 billion to revenue in 2030. Pfizer also has made acquisitions that should help it make up for revenue losses from older drugs. These acquisitions should bring $25 billion in product revenue in 2030.

Yes, Pfizer is at a transition point right now. But the company isn't too far from a new wave of revenue growth. Meanwhile, investors can snap up Pfizer for less than 8 times forward-earnings estimates, and that looks cheap considering potential new products that should drive revenue in the coming years.