Investors should never buy a stock solely because there's a chance that a suitor will buy the company lock, stock, and barrel. However, that doesn't mean that a stock that may attract an acquirer won't also appeal to investors. For instance, our Motley Fool contributors think that these three companies offer investors intriguing reasons to buy beyond an acquisition. Read on to see if these stocks could be a nice fit for your portfolio.

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One biotech that could be up for grabs

Todd Campbell: Few companies have successfully developed therapies that target Parkinson's disease, but Acadia Pharmaceuticals (ACAD -1.39%) is one of them. With evidence that Nuplazid reduced hallucinations and delusions in Parkinson's disease patients during clinical trials, the FDA approved the drug in April.

That approval makes Nuplazid the only FDA-approved therapy for Parkinson's disease psychosis, and investors will soon discover whether or not that monopoly position translates into a blockbuster commercial success. Acadia Pharmaceuticals officially launched Nuplazid on May 31, so third-quarter results should provide some color on how quickly doctors are embracing it. Since about 40% of the 4 million people suffering from Parkinson's disease suffer from psychosis, the potential exists for this drug to be a top seller.

If so, then Acadia Pharmaceuticals would benefit handsomely. Rather than sign on a partner during development, the company retained full global rights to Nuplazid. As a result, if Nuplazid gets off to a strong start, Acadia Pharmaceuticals could be in a prime position to negotiate global rights to the drug, or an outright sale of itself. Potential acquirers wouldn't be limited only to those working on Parkinson's disease, either. Nuplazid is in late-stage studies in Alzheimer's disease psychosis, too. Results from a phase 2 Alzheimer's disease trial are anticipated later this year, and if those results are solid, it could significantly expand Nuplazid's addressable patient population. Between 25% to 50% of the 5 million Americans suffering from Alzheimer's disease also suffer from Alzheimer's disease psychosis.

Admittedly, investors could already be pricing a premium for a potential merger or acquisition into shares. Despite lacking sales and spending $72 million on expenses last quarter, the company's market cap exceeds $3.2 billion. Nevertheless, Nuplazid's potential makes me think that Acadia Pharmaceuticals could fetch even more than that from an acquirer. Of course, that depends a lot on Nuplazid's sales ramp and the upcoming Alzheimer's disease data, so investors will want to stay tuned.

Image source: Workday.

An enterprising cloud play

Steve Symington: After its exceptional fiscal second-quarter 2017 report, I think cloud-based HR and operations software company Workday (WDAY -1.34%) is ripe for the picking. Workday only just expanded its multiyear strategic partnership with IBM for example, and Big Blue will use Workday's Human Capital Management (or HCM) solution to support its entire global workforce of more than 350,000 employees. Workday also welcomed Samsung last quarter as its first South Korean customer, while Dell expanded its use of Workday's products to 125,000 employees given its impending purchase of EMC.

That's not to say the purchase would be cheap, as Workday currently sports a market capitalization of more than $17 billion. And it would need to be on the terms of co-founders David Duffield and (CEO) Aneel Bhusri, who control Workday's votes through a dual-class stock structure they adopted after their previous company, PeopleSoft, was acquired in a hostile takeover by Oracle over a decade ago.

But the appeal is still there with the highly competitive win rates of Workday's core HCM products, which serve as an effective gateway for the company to upsell to other complementary products. Last quarter, almost a third of all new customers purchased Workday Financial Management. And Workday has already secured more than 50 new customers for its Workday Planning product, which will launch with its Workday 27 release within the next month. And that's not to mention the coming releases of Workday Learning, which focuses on encouraging career development for employees, and Workday Student, an education-focused app.

In the end, I think Workday could be an attractive acquisition candidate for a number of tech behemoths looking to streamline costs while establishing a solid presence in the enterprise cloud application market.

A winning combination

Jason Hall: I love my Fitbit (FIT) Charge HR. Since I started wearing it this past winter, I've regularly and consistently improved my activity levels. And in no small part because I'm a data junkie, but most importantly because I've been able to put the data it gives me to good use, making sure I get enough sleep and make time to exercise. 

But I'm not sure that such a pure-play company as Fitbit is really set to succeed for the long term on its own. Sure, it offers a wide range of devices for many needs and lifestyles, but my biggest fear is that the company will at some point feel the pressure to diversify for growth and end up "diworsifying," as legendary investor Peter Lynch would put it. That's why I think it would be an ideal acquisition for Under Armour (UAA 0.75%) (UA 0.61%)

Over the past couple of years, Under Armour has spent hundreds of millions of dollars to acquire several fitness apps, including MapMyFitness, MyFitnessPal, and Endomondo, as well as developed its own UA Record app. More recently, it launched the UA Healthbox, a $400 suite of connected products designed to work with its apps. 

The endgame for CEO Kevin Plank is fully integrated technology embedded in Under Armour's products. The company has started with its running shoes, but that's only the beginning. Furthermore, truly wearable tech is a threat to a stand-alone Fitbit, taking a bite out of the addressable market for its wrist-based products. 

But by becoming part of Under Armour, Fitbit's technology and expertise could accelerate the development of true wearables, a good thing for both companies. It's an unlikely pairing, but one that I think would be a great match.