If you snapped up shares in Snapchat at their recent IPO, you might want to worry today. Facebook has rolled out Messenger Day --and it's looking like it might be a serious Snapchat threat.

Open Messenger and you'll now see a strip of thumbnails above your contact list. Select a thumbnail and you'll get a series of connected images and videos created by your contacts that together form a "day." As soon as you've finished watching one friend's day, the next begins. The content is only available for 24 hours, and as you create your own day, you can add filters to your images, write captions, and draw doodles. You can't determine how long an image or a video remains visible nor can you see how many people have viewed your day but you can see who has viewed it and you restrict views to particular contacts.

In short, you can do many of the things that you can already do on Snapchat. And Day is just getting started.

The feature has already been tested in countries including Poland and Australia, and it's now being rolled out worldwide on both iOS and Android, as well as on desktops.

Now, this is pretty much a straight-up copy of the feature that's turned Snapchat into a multi-billion dollar business, and when Snapchat came up with Stories it was great. But Snapchat's audience is limited. The demographic is young and compared to the billion or so people who use Messenger, it's also small. If you like Snapchat's Stories but you're already invested in Facebook, why wouldn't you use Messenger Day to reach so many more people?

It's a move that really puts Facebook on its way towards global social media domination. Whatsapp, which Facebook owns, has status settings. Instagram, which Facebook also owns, has its own version of Stories. Now Facebook's platform itself has a version of stories so almost everywhere you look, if you want to create temporary, visual content messaging, Facebook has the market sewn up.

The move isn't a big surprise. It was one of my predictions for 2017, and Facebook won't be resting on its laurels. The big feature missing is the ability to post a "day" from Messenger into a public page. You can pull images and video from your device and add them to a day, and you can post the same content on Facebook, but you can't yet take the entire day and share it to your page. Expect that to change.

And custom geofilters? Facebook already has geolocation down. Seeing that monetization is one of Zuck's Prime Directives, I would expect the ability to create paid geofilters for special events will happen within the next year.

Then there's the hardware question. While Facebook's Oculus Rift VR glasses haven't been a massive hit, I'd expect to see a version of Facebook Goggles sometime soon to rival Snapchat's glasses.

Facebook's biggest advantage has always been the size of its massive user base. Everybody's there. As long as Facebook can take features that users love on other platforms and make them available to their own users, those other platforms will always have reason to worry -- and so will their shareholders.

Personally, I'd like to see Snapchat succeed if for no other reason than competition breeds innovation. But there is trouble brewing.