Cold, hard cash. Getting it is frequently one of the main challenges for biotechs, particularly those with no approved products. But several of the largest biotechs currently sit on mountains of cash they can use to reward shareholders in multiple ways.

The three biotechs with the biggest cash stockpiles are Gilead Sciences (GILD -0.69%), Amgen (AMGN -1.27%), and Celgene (CELG). Here's how much money these companies have -- and what they're likely to spend it on.

A huge pile of money wrapped in neat stacks.

Image source: Getty Images.

1. Gilead Sciences

Gilead Sciences ranks at the top of the list with cash, cash equivalents, and short-term investments totaling $30.2 billion as of June 30, 2019. The big biotech's cash position increased dramatically beginning in 2015 as its hepatitis C virus (HCV) drugs generated huge sales.

While Gilead's HCV franchise isn't the huge moneymaker that it was a few years ago, it's still an important source for the company's ample cash flow. The most important revenue generator for Gilead now, though, has been its mainstay for much of the company's history: its HIV lineup. 

Gilead reported $6.68 billion in revenue in the second quarter. Around $4 billion of that total stemmed from its HIV drugs, with powerful HIV treatment Biktarvy leading the way. Thanks largely to the strength of its HIV franchise, Gilead generated $2.2 billion in operating cash flow during the quarter.

Gilead is using its cash in four primary ways. It's using some cash to pay down its debt of around $26 billion. It continues to pay out quarterly dividends and increase the payout annually. Gilead's dividend currently yields 3.8%. The biotech used $1.4 billion in the first half of 2019 to fund share buybacks.

But the biggest use of its cash is coming, with Gilead announcing a $5.1 billion expansion of its collaboration with Galapagos in July. 

2. Amgen

Amgen takes the No. 2 spot with a cash position of $21.8 billion at the end of its last quarter. The company's cash stockpile increased significantly through late 2017 but has been nearly cut in half since early 2018.

Blockbuster drugs, including Enbrel, Neulasta, Prolia, Xgeva, and Aranesp, continue to rake in impressive sales for Amgen. However, several of its top drugs now face stiffer competition, with biosimilars and generic versions on the market.

Amgen has some other drugs that could make bigger contributions in the future. Analysts think that migraine drug Aimovig, which Amgen copromotes with Novartis, could achieve peak annual sales of $1.2 billion. Amgen expects strong sales growth for leukemia drug Blincyto, multiple myeloma drug Kyprolis, and its lineup of biosimilars, as well.

The company doesn't plan to sit on its huge cash stockpile for much longer. Amgen plans to soon use $13.4 billion of its cash position to buy blockbuster drug Otezla from Celgene. It also has committed to returning more cash to shareholders through higher dividends and stock buybacks. In addition, Amgen has publicly stated that it's open to more business-development activities, including potential acquisitions.

3. Celgene

Celgene's cash, cash equivalents, and short-term investments totaled $9.32 billion at the end of June. Its cash position will increase significantly with the sale of Otezla to Amgen. This divestiture was required to pave the way for Bristol-Myers Squibb's (BMY -0.59%) acquisition of Celgene.

By far the biggest contributor to Celgene's nice cash stockpile is its powerhouse blood cancer drug Revlimid. Multiple myeloma drug Pomalyst and solid tumor drug Abraxane have also added plenty of money to the biotech's coffers, along with the soon-to-depart psoriasis and psoriatic arthritis drug Otezla.

While Celgene's current lineup is impressive, the biotech's pipeline played a key role in attracting interest from Bristol-Myers Squibb. Celgene has four potential blockbusters on the way within the next couple of years: multiple sclerosis drug ozanimod, cancer cell therapies liso-cel and bb2121, and blood cancer drug luspatercept.

With the acquisition by Bristol-Myers Squibb expected to close later this year or in early 2020, Celgene itself probably won't be using too much of its cash stockpile going forward. However, its cash makes the $74 billion price tag that Bristol-Myers Squibb is paying for the buyout less burdensome.

Which of these stocks are worthy of your cash?

Investing in biotech stocks simply because they have big cash stockpiles isn't a smart move. However, I think that two of these three cash-rich biotechs are good picks.

I'm not a fan right now of Amgen, though. It's not a bad pick for dividend investors, but my view is that Amgen won't deliver a lot of growth over the next several years.

Gilead Sciences, on the other hand, could return to stronger growth after several years of declining revenue with its HIV franchise growth and a potential new blockbuster in filgotinib, assuming the drug wins approval in treating rheumatoid arthritis.

While Celgene is about to be gobbled up by Bristol-Myers Squibb, I don't think it's too late to buy the biotech stock. Celgene shareholders could get a $9 per-share sweetener, thanks to a contingent value right (CVR) linked to the Food and Drug Administration's approvals of ozanimod, liso-cel, and bb2121. I also think that holding on to Bristol-Myers Squibb shares after the acquisition of Celgene finalizes could be a good move.