I have in the past gone through two hostile takeovers (one from the acquiring and one from the acquired side) and two mergers of major companies. In all cases, the lower down the ladder you were, the more likely you were of keeping your job. It was the folks at the upper end who found themselves, as the British say, Made Redundant. (Of the four, the only time I lost my job was the hostile takeover when we were acquired; they closed the entire division as the acquiring company already had an office in our city. Not one of us was absorbed into the existing location. However, no one in any of our other nine locations lost their job.
For what it's worth.