It would appear that StumbeUpon is no longer a company with a CEO. There hasn’t really been a lot of clarity around this in recent months, but that appears to be the state of things.

Over two years ago, StumbleUpon (under CEO Mark Bartels) made its first acquisition with 5by – a video discovery service that operated much like StumbleUpon itself, but strictly for videos. It was a pretty cool app, particularly once it became Chromecast compatible, and seemed to be a major part of where StumbleUpon was headed.

On Thursday, an email was sent to 5by users saying that it is shutting down. While I was well aware that StumbleUpon has been going through some changes, I can’t say I saw that coming.

Digging a bit after receiving that email, I discovered much to my surprise neither Bartels nor 5by CEO Greg Isenberg are even at the company anymore. I’ve seen no reports of either leaving, which seems strange to me particularly in the case of Bartels. We’re talking about the CEO of what is one of the web’s biggest drivers of social media traffic to websites. If he left the company, it seems like we should’ve heard about it.

As you may know, co-founder Garrett Camp announced in August that he was returning to the company, purchasing the majority stake, and advising management. He wrote:

Some difficult changes to the product and company will be needed, and these changes will take time. But I strongly believe that systems like StumbleUpon play an important role in helping people discover what matters most to them. I’m excited to work with the team on product once again, getting back-to-basics and improving recommendations, while exploring potential synergies between SU and Expa.

He noted that he is still focused on being CEO of Expa, his startup studio (which counts Uber among its companies by the way).

While layoffs were known, there was no mention of the departure of Bartels, Isenberg, or even 5by at all. According to Bartel’s LinkedIn profile, he exited StumbleUpon in September. I’ve also learned that Isenberg has been gone since June.

So what does that mean for StumbleUpon? Well, Camp actually announced what is going on with StumbleUpon on October 30th. Apparently nobody (at least in the media – myself included) noticed it.

Expa has begun working on a new discovery platform called Mix.com, which aims to “connect the curious with the creative, delivering personalized recommendations one click at a time.”

That sounds exactly like StumbleUpon.

“Mix will provide a modern and elegant way to discover the best content liked by friends and experts, from across the web to your mobile device,” Camp wrote.

He also said that StumbleUpon is officially part of the Expa family and that the StumbleUpon team will be joining forces with Expa to create Mix.com, “bringing with them everything learned serving 50 billion recommendations to millions of people.”

According to this announcement, StumbleUpon users will be able to use the site like normal and it will “continue to operate as always” as Expa explores new product ideas for Mix. My guess is that StumbleUpon will go away once Mix is ready for primetime.

While plenty of websites still get a ton of traffic from StumbleUpon, it’s clear (and made even more so by the lack of coverage around this) that StumbleUpon just doesn’t draw the interest that it once did. This evolution could be just what it needs.

The reality is that StumbleUpon still operates within in an area in which it isn’t really rivaled. There aren’t really any other services of note that do what StumbleUpon does, which is obviously why Camp is still pursuing this kind of content discovery.

Image via Mix.com