Nothing can ever be absolutely shocking in the biotechnology and healthcare world.

I’ll admit though that the reports on AstraZeneca’s (AZN) interest in acquiring Gilead Sciences (GILD) surprised me.

The two companies touched base last month on a potential acquisition deal.

If this rumor turns into a reality, then we’re looking at what could be the biggest healthcare deal to date.

That’s saying something considering the massive mergers we’ve seen in the past years.

So far, the biggest biotechnology and healthcare deal is the $87.6 billion acquisition of Celgene (CELG) by Bristol-Myers Squibb (BMY) in 2019.

In the same year, AbbVie (ABBV) acquired Allergan (AGN) for a whopping $83.8 billion, making it the third biggest deal in the healthcare sector to date.

The year 2018 paved the way for two more massive deals in the form of Takeda’s (TAK) $81 billion acquisition of Shire, which ranks fourth overall, and Cigna’s (CI) $68.4 billion deal with Express Scripts (ESRX) in seventh place.

Fifth on the list is by Sanofi’s (SNY) $73.5 billion deal with Aventis in 2004.

Although it has been two decades since it happened, the $72.5 billion merger of Glaxo and SmithKline Beecham in 2000 still counts as one of the biggest deals in the industry. This agreement gave birth to GlaxoSmithKline (GSK).

Prior to Bristol-Myers Squibb and Celgene deal, it was Pfizer’s (PFE) $87.3 billion acquisition of Warner-Lambert in 1999 that topped the list.

AstraZeneca’s current market capitalization is roughly $140 billion. Meanwhile, Gilead Science’s market cap stands at approximately $96 billion.

With all these in mind, the AstraZeneca-Gilead Sciences merger is estimated to reach roughly $250 billion on top of the significant synergies expected throughout the years.

If these two health industry heavyweights merge, then their newly formed company would become the third biggest healthcare company in the world behind Johnson & Johnson (JNJ), which has a market cap of $384.55 billion, and UnitedHealth Group (UNH) with $293.85 billion.

Looking at this potential merger in the context of the coronavirus race, it’s safe to say that the combined efforts of AstraZeneca and Gilead would create a COVID-19 titan.

AstraZeneca’s partnership with the University of Oxford resulted in a COVID-19 vaccine candidate that was recently selected as one of the top five candidates worthy of US government support through Trump’s Operation Warp Speed program.

Meanwhile, Gilead’s antiviral medication Remdesivir has been constantly hailed as the standard of care for COVID-19 treatment since the pandemic broke.

The drug which was previously marketed as an HIV medication is now expected to generate $2 billion in sales as a COVID-19 treatment in 2020 alone.

In 2022, Remdesivir is estimated to rake in roughly $7.7 billion in sales. After that, the antiviral drug is projected to generate annual sales somewhere between $6 billion and $7 billion.

Although everything is hypothetical, let’s take a quick look at where each company stands at the moment outside their COVID-19 efforts.

AstraZeneca has been a consistent strong stock market performer throughout the years.

In the first quarter of 2020, sales improved in practically all of AstraZeneca’s territories. Although it has a diversified portfolio of drugs and a robust pipeline, the company’s hottest segment is its oncology business.

A good example of this is non-small cell lung cancer treatment Tagrisso, which is starting to live up to expectations as the next mega-blockbuster for AstraZeneca.

The cancer drug’s first quarter sales reached an impressive $982 million, showing off a 56% jump year over year.

This is promising considering that its competitors include Roche’s (RHHBY) Tarceva and Eli Lilly’s (LLY) Cyramza.

As for its 2020 revenue forecast, AstraZeneca is reported to rake in $25 billion, from which it will generate approximately $7.5 billion in operating profit.

On the other hand, Gilead also has an impressive portfolio that it can bring to the table.

In the first quarter of 2020, the company earned $5.47 billion in revenue compared to the $5.20 billion it generated in the same period last year.

Despite the decline in its hepatitis products from $790 million in the first quarter of 2019 to $729 in the same period of 2020, Gilead’s HIV line made up for the loss by bringing in over $4 billion in sales compared to the $3.6 billion it earned last year.

Not only that, some of Gilead’s other candidates are exciting.

For example, rheumatoid arthritis drug Filgotinib is expected to become another blockbuster and generate $5 billion in revenue annually.

Meanwhile, the anti-tumor treatment Magrolimab is estimated to rake in $3 billion in peak sales.

With the company’s older drugs still capable of generating strong revenue and its new candidates showing their potential for revenue expansion, Gilead can be assured of a continued cash flow well into the 2030s.

Regardless of whether this rumored mega-merger pushes through, both Gilead and AstraZeneca are attractive stocks worthy of their premium valuations.