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The Internet of Things can be a volatile space. Over the next five years, Cisco Systems estimates that nearly 50 billion things will be connected to the Internet, allowing for an unprecedented amount of data collection and analysis, as well as automation. 

While there are a handful of Internet of Things (IoT) pure-play stocks out there, many companies that are making big bets in the IoT space are also big players in other segments. The three stocks below may not be the first you think of when it comes to the Internet of Things, but all have made major IoT moves this past year and their stock has made investors very happy at the same time.

NVIDIA: Up 60% year to date
Back in January, I wrote that NVIDIA (NVDA -10.25%) is one Internet of Things stock investors may be overlooking, but considering its stock spike later in the year, it appears many investors may not have been overlooking it after all. 


Source: YCharts.

The company is known for its processors and mobile gaming systems, but its growing opportunity comes from making Tegra processors with deep learning and situational awareness abilities for semi-autonomous and autonomous vehicles. NVIDIA's chips have already helped a 560-horsepower Audi RS7 drive around a race track by itself and helped drive an A7 from San Francisco to Las Vegas almost entirely on its own.

NVIDIA's tapping into the growing autonomous vehicle market, which will have an estimated worth of $42 billion by 2025. Over the next 10 years, there will be 18 million semi-autonomous cars and 12 million fully autonomous cars on the road, according to Boston Consulting Group. 

In addition to its chips, the company's also created the Drive PX platform, which allows car companies to easily implement an autonomous driving system into vehicles. And NVIDIA says about 50 car companies and start-ups are already starting to use the system.

Speaking about autonomous vehicle opportunities on the company's earnings call back in November, NVIDIA CEO Jen-Hsun Huang said, "And this is an area where we really have a great deal of capability. It's going to require sensor fusion, it's going to require an enormous amount of software, it's going to require artificial intelligence and it's going to require the ability to support an open computing platform that NVIDIA is built upon." 

And as the autonomous vehicle market grows, there appears to be plenty of room for NVIDIA to grow along with it. 

Alphabet: Up 40% year to date
Obviously, Alphabet (GOOG -1.32%) (GOOGL -1.46%) isn't only interested in the Internet of Things. Google's parent company has its hands in so many businesses it's often hard to keep up with them all, but the company continues to make big moves in IoT.

Google's ambitions in the self-driving space are already well-known, as is its purchase of the home IoT company Nest, but the company's IoT ambitions go far beyond these.


Source: YCharts.

Earlier this year, Alphabet announced a new, open-source IoT platform called Brillo. The platform's goal is to be a sort of Android for the Internet of Things, allowing developers to create IoT devices that can easily collect and communicate data with each other. This, combined with Google's Cloud Platform, are helping to pave the way for a surge of Internet-connected devices. 

If that weren't enough to prove Alphabet's IoT chops, the parent company is also working on nanoparticles that travel in a user's bloodstream and search for cancer and other diseases. The nanoparticles are then magnetically attracted to a wrist-worn device where they report their findings. That may seem like science fiction, but it's clear that under Alphabet, Google is continuing to pursue a plethora of IoT ambitions. 

Amazon: Up 114% year to date
Sure, Amazon (AMZN -2.87%) may seem like an unlikely Internet of Things stock. But this year, the company dove head first into the IoT and delivered gains of over 100%.


Source: YCharts.

Amazon debuted several IoT services in 2015, including its Dash Replenishment Service (DRS), which allows companies to build DRS into their own products. Whirlpool is using DRS in some of its new washing machines so that they can automatically order detergent when they're running low, without the user having to place the order themselves.

Then the company made another big IoT step when it announced that it would open up the brains of its voice-activated Echo smarthome hub, Alexa, to third-party app developers. By doing so, Amazon makes it easy for developers to integrate Alexa into new devices, and encourages them to power Alexa with its Amazon Web Services (AWS) Lambda system. The move could help Amazon boost its own AWS services by having more people use its cloud services for IoT devices.

Additionally, Amazon moved further into IoT in October when it launched its AWS IoT platform. The company says that it "lets connected devices easily and securely interact with cloud applications and other devices." Amazon is looking ahead to a world of billions of connected things -- and it wants to be the cloud company that powers the data collection and analytics for all of those devices.

While none of the stocks above are Internet of Things pure plays, they've all rightfully earned their place in the IoT -- and investors would be wise to keep watching them closely in this space.