ZS associates guy here who is called in during reorganization and M & A efforts. To be clear, I'm not involved/contracted for this deal.
I can tell you in other deals I've done there is a common theme affecting the acquired:
Managed care teams first to go
Research last to go
Field employees (managers,reps,other) with a base salary 150k or higher first to go.
Buildings/material assets take 1.5 years to shop off.
Companies try to seal the deal quick as they know employees will fart around. You can bet deal is done 2q not 3q. They must provide a mass layoff [WARN] act 60 days prior to your last day.
Tip- if you feel you are at risk and get an offer elsewhere, don't deny and wait for severence. Accept the job, call HR and ask for an "accelerated separation agreement". You can still get the other job and your severence. Believe me, they want people off the books voluntarily, call it hush money.
Feel free to post any questions....and to clear up rumors, Merck let 72% of SP employees go in that deal.
If you stay on, read your benefits wisely! Legacy BMS reps will have their same modeling and you might have a post merger version B which is not the same.
Read the fine print, not here on CP but from your HR department.
Good luck, you will get through this.