My experience with this, was a startup that got bought out. First, there were a number of all hands meetings assuring that everyone was staying, and to "you are free to buy that new car, as you don't have to worry about losing your job." Red flag #1.
Then management changed. The person in charge went from actually caring about IT to being very dismissive. After that, we had employees from the main company present "just to learn workflows." Red flag #2.
Then, employee reviews rolled around, and my previous OK review became a kangaroo court session of he said/she said stuff. For example, the manager commented about a staged rollout that went successfully, "The vendor knows their software and has tested more than you ever will. Why are you wasting your time with just not having machines fetch and update by themselves?" Yep, third strike, red card on the field.
I started my job hunt. A few days later, the Windows admin got fired for "failing to maintain uptimes comparable to the UNIX side of the house, as the Solaris boxes had 100-200 day uptimes, and Windows boxes were never up more than a month". I started looking in earnest, removed everything off my desk, made sure anything personal was gone, flushed social media, and so on.
When I got the Outlook notification on the calendar about an unexpected meeting, I handed my "bus book" to the admin from the parent company who was "just there to learn things", asked for references, moved my car out of the parking lot and onto the street. Come meeting time, I saw the manager slink off the opposite direction, and the recently moved team lead present. Before the lackey finished inhaling, I handed him my badge, making the guy stammer and get a deer in headlights eyes, because I short-circuited his prepared firing speech. I then asked him to do the formalities of the march to the entrance, and that maybe the manager could get the cojones to at least face members of his team he is firing.
The whole gist of the fiasco is that the owning company wanted to lay off all the workers in the company bought out, but didn't want to have it public, so all the IT people got fired for vague causes, just to get around the WARN act.