It's an understatement to say 2019 has been a frustrating year for shareholders of Fitbit (NYSE:FIT). Shares briefly rallied at the start of the year on hopes that its first full-featured smartwatch, the Fitbit Ionic, might spur a long-awaited return to sustained, profitable growth. But with its turnaround seemingly failing to materialize and as its subsequent smartwatch offerings faltered, Fitbit stock plunged to fresh multiyear lows last month.

Investors were granted some consolation over the past few days, however, when shares popped as Reuters reported Fitbit has enlisted the help of investment bank Qatalyst to determine whether it should put its business up for sale.

But with Fitbit's market capitalization standing at roughly $1 billion as of this writing, who might be willing to acquire the wearable fitness tech device specialist today?

Here are a few companies I think fit the bill.

Woman drawing large yellow fish eating a smaller fish.

IMAGE SOURCE: GETTY IMAGES.

"A" is for acquisitions

First, sources speaking with Reuters specifically listed either private-equity firms or Alphabet (NASDAQ:GOOG) (NASDAQ:GOOGL) subsidiary Google as the most likely suitors for Fitbit.

Google makes the most sense to me. After all, Fitbit already has a partnership with Google revolving around integration with the search giant's Google Cloud Platform and Cloud Healthcare API. With more than $121 billion in cash on its balance sheet and a long history of acquisitions -- including its $12.5 billion purchase of Motorola Mobility in 2011, a bevy of robotics companies in 2013, and $3.2 billion for smart-thermostat maker Nest in 2014 -- Google could use Fitbit to supplement its existing hardware product portfolio, which also includes its Pixel smartphones, Chromecast streaming devices, and Google Home smart speakers.

That's not to say Google would simply rebrand Fitbit's products as its own. Note it subsequently sold Motorola to Lenovo, for example, while retaining the company's patent portfolio -- so Big G might be primarily interested in obtaining Fitbit's intellectual property to both improve on existing products and develop its own novel wearable fitness devices down the road.

A drop in Cupertino's bucket

Speaking of cash, Apple (NASDAQ:AAPL) could put a small fraction of its own $259 billion war chest to work by absorbing Fitbit in a similar fashion. With Apple's own fast-growing wearable business set to enjoy a boost from the recently unveiled Apple Watch Series 5, however, I suspect Apple wouldn't be too keen on integrating Fitbit's relatively simplistic wearables into its own highly engineered, feature-rich lineup.

Put simply, if Apple were to acquire Fitbit, the move would be less complementary and more about building IP while removing a competitive threat from the wearable tech niche. Assuming multiple parties are interested in striking a deal, I suspect Fitbit would be resistant to pursuing such a transaction.

An established fitness-tech innovator

Finally, I wouldn't be surprised if Nike (NYSE:NKE) dropped its name into Fitbit's prospective acquirer hat. The athletic footwear and sportswear giant briefly tried its hand in the space with its FuelBand fitness tracker, only to discontinue the device after it proved difficult to take market share from Fitbit in the early stages of the industry. Instead, Nike shifted its focus to other high-tech projects like its smart connected shoes, mobile apps, and various partnerships with Apple, including a Nike-branded variant of the Apple Watch.

And Nike isn't afraid of making strategic investments, including acquisitions, to extend its market leadership and accelerate growth. Most recently to that end, Nike acquired mobile retail start-up Virgin Mega (in August 2016), followed by consumer and retail data analytics firms Zodiac (in early 2018) and Celect (just last month). In each case, however -- unless you rewind all the way back to Nike's acquisitions of Hurley and Converse in 2002 and 2003, respectively -- these were relatively small businesses that don't offer tangible consumer products and focus primarily on improving its retail analytics and digital-shopping capabilities.

Still, Nike's vast resources, supply chain expertise, and retail connections could certainly take some pressure off Fitbit as it implements its turnaround.