Warren Buffett built a fortune over the past few decades. Hailed as the greatest contemporary investor, the "Oracle of Omaha" now, at the age of 90, has billions of dollars at his disposal to invest as the CEO of Berkshire Hathaway. But successful investing doesn't hinge on having access to Buffett-level resources.

With as little as $100, investing in stocks can work wonders, provided you do so shrewdly. In that spirit, here are two stocks, both well under $100 per share, that are worth your hard-earned money: Exelixis (EXEL -0.07%) and AstraZeneca (AZN -0.43%). Read on to find out why you don't want to miss out on these investments. 

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AstraZeneca -- about $55 per share

AstraZeneca has been collaborating with the University of Oxford to develop a vaccine for COVID-19, and the two partners are currently running late-stage studies in several countries. The company's efforts recently hit a roadblock, however.

A participant in a phase 3 clinical trial in the U.K. for its candidate, AZD1222, suffered an unexplained illness. AstraZeneca paused its ongoing clinical studies as a result. The U.K.-based drugmaker argued that such adverse reactions would happen by chance in large clinical trials. At any rate, there was no evidence that AZD1222 was responsible for the illness. 

Authorities in the U.K., Japan, Brazil, South Africa, and India gave AstraZeneca the green light to continue its trials -- although authorities in the U.S. have yet to do so. Furthermore, the European Medicines Agency started a rolling review of AZD1222.

This allows a company to submit parts of the data for review, rather than submitting the entire application all at once; the rolling review process could expedite the approval of AZD1222. AstraZeneca has long been considered a leader in the COVID-19 vaccine race, and the company's candidate could have a bright future ahead. 

Piggy bank wearing a face mask.

Image source: Getty Images.

Beyond its COVID-19 program, AstraZeneca boasts several drugs whose sales are growing rapidly. During its second quarter, which ended June 30, revenue from cancer drug Lynparza grew by 48% year over year to $419 million. Imfinzi, another cancer medicine, saw its sales soar to $492 million, 46% higher than the prior-year quarter.

Still in AstraZeneca's oncology department, Tagrisso's sales jumped by 32% year over year to about $1 billion. Elsewhere, the company's diabetes medicine Farxiga recorded revenue of $443 million during the second quarter, 17% higher than the year-ago period. Sales of asthma treatment Symbicort were $653 million, a year-over-year growth of 12%. 

Overall, the company reported total revenue of $6.3 billion, an improvement of 8% compared to the second quarter of 2019. The company's core (non-GAAP) earnings per share of $0.96 jumped 32% year over year. With 166 programs in its pipeline -- including nine in phase 3 studies -- AstraZeneca is poised to continue replenishing its lineup.

In my view, the company's AZD1222 will be a commercial success, and thanks to its strong existing portfolio of products and its rich pipeline, AstraZeneca will continue growing its revenue and earnings at a good clip. Adding shares of this pharma stock to your portfolio today would be a great move. 

Exelixis -- about $24 per share

Exelixis' main claim to fame is Cabometyx, a cancer drug approved for the treatment of renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC). RCC is a form of kidney cancer, while HCC is a type of liver cancer. Cabometyx is the only RCC drug of its kind to achieve significant improvement in three key efficacy parameters: overall survival, objective response rate (the percentage of patients whose cancers reduce after treatment), and progression-free survival (the amount of time during and after treatment the patient lives with cancer without experiencing worsening symptoms).

The cancer treatment is the top-prescribed tyrosine kinase inhibitor (TKI, a type of drug that specifically targets cancer cells) for RCC in the U.S., and also holds a strong share of the HCC market.

The coronavirus has affected Exelixis's business. During the second quarter, which ended June 30, the company's net product revenue decreased to $179 million, down from the $194 million it recorded during the second quarter of 2019. The decrease was due to lower sales volumes caused by the pandemic.

Microscopic rendering of cancer cell.

Image source: Getty Images.

While Exelixis's total revenue did increase by roughly 8% to $259.5 million, that was due to higher revenue from collaborations. Exelixis will likely rebound once the outbreak subsides.

Cabometyx is undergoing more than 50 clinical studies -- both as a standalone medicine and in combination with other drugs.And in July, Exelixis announced positive results from a phase 3 clinical trial of the drug in combination with Bristol Myers Squibb's Opdivo and Yervoy as a therapy for advanced or metastatic RCC. Exelixis believes this could open the door to an increased market share for Cabometyx.

Management can look forward to Cabometyx adding many more indications, with increasing sales to follow. The company's revenue and earnings will follow suit. And in the meantime, Exelixis's shareholders will likely enjoy some healthy gains.