September hasn't been brilliant for stocks so far. The S&P 500 has dropped 5.2% through last week, and a tech stock rout left the Nasdaq down 8.3%. With the coronavirus crisis still around and the presidential election ahead, the market turmoil may not be over. So it's time to be proactive and start stocking up on shares that will be long-term winners. That means companies with strong products. They will generate sales during tough times and beyond.

We often think of coronavirus stocks as those that offer massive short-term gains (and the risk of similar losses). But today, I'm talking about three companies with promising coronavirus work and huge portfolios of other successful products. They represent a way to invest in the coronavirus market, with lower risk. And that makes them the perfect additions to your portfolio ahead of a crash.

Man in front of board showing falling financial figures

Image source: Getty Images.

Abbott Laboratories

In a matter of months, Abbott Laboratories (NYSE:ABT) has become a coronavirus testing giant. The U.S. Food and Drug Administration (FDA) has granted emergency use authorization to sixAbbott coronavirus tests. And so far, Abbott has provided more than 27 million tests across the country. The latest test to launch is one that could be key in the effort to test entire populations. The test, used to detect active infection, involves portable material about the size of a credit card and provides results in 15 minutes. The company plans to ship as many as 50 million tests a month as of October.

Some of Abbott's coronavirus tests have already contributed to earnings. In the second quarter, they generated $615 million in sales. We should expect coronavirus testing sales growth in the coming months as more and more Americans want or require testing. At the same time, recovery is likely ahead for sales of Abbott's other tests and medical devices. Most suffered in the early days of the outbreak as clients postponed nonessential procedures. An exception was diabetes care. Sales of Abbott's FreeStyle Libre glucose monitoring system rose more than 36% in the quarter. The FDA clearance of a newer version a few months ago may further boost sales. So, in coming quarters, a return to normal for the rest of Abbott's business plus growth in coronavirus tests and diabetes care should be a winning combination.

Pfizer

Pfizer (NYSE:PFE) and partner BioNTech (NASDAQ:BNTX) are among leaders in the coronavirus vaccine race. The big pharma joined forces with the biotech company on a vaccine based on messenger RNA. Instead of introducing weakened virus into the body, mRNA vaccines instruct the body to defend itself. With these instructions, the body makes a version of the target protein that will spur immune system response. Pfizer said it's on track to report efficacy data from late-stage trials by the end of October. And more good news for Pfizer: FDA Commissioner Stephen Hahn recently saidthe agency would consider granting companies emergency use authorization even if phase 3 trials aren't complete.

There's a lot to Pfizer beyond coronavirus work, of course, and that's what makes it a rather safe bet. Pfizer's main revenue driver is biopharma, with the segment bringing in $9.8 billion of the company's $11.8 billion in second-quarter revenue. Vyndaqel, a treatment for a cause of heart failure, and cancer drug Ibrance are among products that led the quarter's 6% gain in biopharma sales. Importantly, Pfizer has 89 programs in the pipeline, and 23 are in phase 3. Pfizer expects the pipeline to contribute to a revenue compound annual growth rate of at least 6% over the coming five years, and top-line growth beyond that point.

Regeneron

If Regeneron Pharmaceuticals (NASDAQ:REGN) is successful with its coronavirus program, the result could be big. The company is developing an "antibody cocktail" to treat and prevent infection. Regeneron screened thousands of antibodies produced by mice (genetically engineered to have human immune systems) and antibodies from recovered coronavirus patients. Researchers chose the two most potent for the product candidate. A phase 3 U.K. study is now evaluating the cocktail in combination with standard of care in the treatment of hospitalized patients. In July, the company launched a phase 3 U.S. trial to examine the cocktail's ability to prevent infection among people in close contact with coronavirus patients -- such as a housemate.

Beyond coronavirus work, Regeneron has six marketed drugs. They include Eylea for wet age-related macular degeneration and Dupixent for atopic dermatitis. Annual revenue has been on the rise since 2012, reaching more than $7.8 billion last year. And the biotech company's earnings have surpassed analysts' estimates for the past four quarters. Regeneron's pipeline of more than 30 programs, including nine in phase 3, makes me optimistic about growth years down the road.

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.