Behind Facebook and Google’s random acquisitions

April 1, 2014, 11:47 PM UTC

FORTUNE — A lot of attention has been paid lately to big tech companies buying up smaller firms in billion-dollar deals: In January, Google acquired Nest for $3.2 billion, Facebook purchased mobile message service, WhatsApp, the following month for $19 billion; last week, it acquired virtual reality gaming company, Oculus VR, for $2 billion. There is a lot of discussion about the motives behind these large deals. Some say they are attempts to block competition, while others maintain they are efforts to stay relevant.

I see these deals as a reflection of the uncertainty companies face as they try to identify the next big thing. This is especially true for successful companies like Facebook (FB) and Google (GOOG), which are known for doing what they do tremendously well. They’ve seen similarly successful companies like Kodak struggle as technology moves on, rendering its product obsolete. As a result, companies today are eternally motivated to look outside their current business.

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Viewed in this light, an acquisition strategy makes a lot of sense. Google is a good example. It excels so much in the search space that this very expertise makes it hard to divert its attention to other things that are not search.

We tend to see this strategy more in the tech space than in life sciences or other areas. This is because the destruction of business models is so much more rapid (and in some ways vicious) in technology. In other spaces, you have at least a few years to see the changes ahead. Even Kodak had a good 10 years after digital cameras were invented to sell film before it became irrelevant. However, you only reap first-mover rewards for a short period in technology. Look at the relatively brief popularity of as an example. I’m sure that this is something that haunts everyone at Facebook.

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Successful tech companies like Google and Facebook know they have to hedge their bets. They have to assume their current product or services will be replaced. And they know that their own imagination may be hampered by the fact that they are so good at what they currently do. They may not be able to envision what the future holds without looking to outside companies. This is why we so often see these large tech companies acquiring smaller ones in adjacent spaces. They are trying to disrupt their current business model rather than acquire something that immediately fits into the current line of business.

So while tech companies are certainly competitive, that’s not what’s driving these acquisitions. Instead, it’s all about the continuing search for the next big thing.

Catherine Tucker is a marketing professor at the MIT Sloan School of Management.