The period from May through late July tends to be unexciting for biotech stocks, in part because for various logistical reasons, first-quarter earnings are usually ho-hum across the industry. Second-quarter earnings, though, are often much stronger, which provides a spark for share prices. 

With that in mind, let's consider Amgen (NASDAQ:AMGN) and Gilead Sciences (NASDAQ:GILD), both of which released their Q2 results after the closing bell Tuesday. Are either of these biotech heavyweights more compelling buys in the wake of their earnings reports?

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The case for Amgen

Amgen easily topped Wall Street's consensus estimates for both its top and bottom lines in Q2. On the revenue side of the equation, its cadre of growth products -- consisting of the migraine medication Aimovig, the bone density treatment Prolia, the novel cholesterol-lowering drug Repatha, and the hyperparathyroidism treatment Parsabiv -- posted respectable sales growth.

Unfortunately, Amgen also has a host of older drugs that now face generic competition, and declining sales of those treatments propelled total revenues downward by 3% year over year to $5.9 billion. Though the company has more work ahead of it if it's going to move past its avalanche of patent expirations, it did raise the lower end of its full-year 2019 revenue guidance by a healthy $400 million Tuesday, reflecting the strong commercial trajectory of key new products like Aimovig. That's an encouraging sign that Amgen may indeed be turning the corner from a top-line perspective.  

While Amgen's revenues have been heading in the wrong direction this year, it does offer a top-notch dividend that yields 3.29% at current levels, stellar free cash flows that it can use to reward shareholders, and an intriguing lineup of novel cancer drug candidates that are just one segment of a broad pipeline. Best of all, Amgen's shares are only trading at 11.9 times next year's projected earnings, which is a bargain for blue-chip biotech with a juicy yield attached to it. So yes, Amgen's stock is definitely worth considering right now -- despite these mixed quarterly results.   

The case for Gilead

Gilead also posted stronger-than-expected revenue and earnings figures for Q2. The highlight of the report was the incredible sales growth of its new star HIV medicine Biktarvy. Specifically, the drug generated a whopping $1.16 billion in global sales for the period. Biktarvy's success, though, does seem to be coming at the expense of several of the biotech's other HIV medicines: Atripla, Complera/Eplivera, Descovy, Genvoya, Stribild, and Truvada have all experienced sizable sales declines over the past year. 

Gilead also reported that the anti-cancer cell therapy Yescarta hauled in a noteworthy $120 million. While that amount might seem impressive at first glance, it's a far cry from where many thought the therapy would be at this point in its commercialization. Point blank, it could take the better part of the next decade for Gilead to simply break even on its $11.9 billion acquisition of Kite Pharma's adoptive cell therapy platform. 

The most compelling reasons to buy this biotech stock right now are its dividend, which currently yields a handsome 3.77%, and its intriguing clinical pipeline. Gilead is, for instance, close to filing regulatory applications in both the U.S. and EU for the anti-inflammatory medicine filgotinib as a treatment for rheumatoid arthritis. The drug candidate has the potential to generate billions in annual sales.

That said, based on the performance of Gilead's shares this year, the market clearly wants more out of the biotech on the business-development front. Stated simply, you probably shouldn't buy this stock expecting to turn a quick profit. Gilead is clearly a long-term play, even though the company's quarterly figures have been steadily improving in 2019.  

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.