To me it's kinda obvious that any "major event" i.e. merger, large acquisition, split, extremely bad quarter etc. in a big company is an excuse to let people go

To me it's kinda obvious that any "major event" i.e. merger, large acquisition, split, extremely bad quarter etc. in a big company is an excuse to let people go. IMO the only way to survive these "events" in a big company is to make sure you are indispensable (which is not a reflection of how smart you are) or be politically astute. Despite this there are no guarantees, you just have to keep your eyes and ears open to the on goings of your company.