If you own stock in Fitbit, the fact that Google appears to be interested in buying the wearable-device maker is very good news. If, on the other hand, you own and use an actual Fitbit, it could be really bad news. According to Reuters, the world's largest search engine's parent company, Alphabet, is looking to make a purchase to beef up its wearable technology. As a result, Fitbit's shares rose 27 percent after trading was temporarily halted, bringing the company's value to $1.4 billion.  

That's certainly good news if you're an investor, but ask yourself whether or not you're comfortable with Google suddenly having access to even more of your personal information.

I wrote this summer about the evolution of Nest, and what effect Google has had on that company, particularly in how it handles user data and personal information. The bottom line is that Google isn't shy about the fact that it will use your information, including information gathered by Nest, to market to you.

Imagine what that looks like when the device capturing information is something you wear all the time. It knows your activity, your heart rate, and in many cases, your location. Google hasn't exactly shown that it's willing to keep that kind of information siloed from the data it uses to market to you, meaning it isn't that hard to imagine it might be interested in Fitbit entirely because of the information it gathers about you all day and night.

Google is, at its core, a software company that makes money selling ads based on users' personal information: search habits, purchasing, locations, etc. It tracks what you do online, it knows who you communicate with, and if you use an Android device, it knows every app you use, and where you use them.

That's a lot of information, and Google has been wildly successful at monetizing that data. In fact, it's the largest advertising platform in the world as a result of its ability to turn your data into cash for advertisers and for itself.

That's not to say Google isn't good at building hardware. It actually makes some interesting phones and smart home devices--largely because of its purchase of Nest. But the hardware isn't really the point. The information is.

In fact, most of Google's current hardware serves really no other purpose than to provide a vehicle for additional data collection. I'm serious--the only reason a Google Pixel smartphone exists is to provide a pure Android experience. The only reason Google makes Android is because your smartphone is by far the greatest source of personal data in your life.

If Google didn't make those devices, you'd be buying them from someone else, like Amazon or Apple and Google wouldn't be able to draw upon your activities and data. Actually, if you already are buying wearables, it's likely from Apple, which means Google is already behind. 

That explains why Alphabet's stock rose 2 percent on the of the news of the possible FitBit purchase as well. It can use all the help it can get to catch up, and certainly FitBit would be a huge boost. The problem is whether or not what's good for Google is good for you.