>Receiving this information out of the blue has caused my heart to skip a beat and left me nervous. I feel a sudden loss of security. Are my fears founded? Should I calm down and wait to see how things progress? Is it time to polish my resume?

I've been through many acquisitions and mergers. Sometimes things change immediately. Sometimes things stayed the same while my company was "integrated". Eventually, I left all of them.

Think of it this way - would you have applied to work at Acme Co. if they hadn't merged with your employer?

Polish up the resume. Tune up the professional network.

Wait to see how things proceed, but be ready to go when necessary. It might work out, but it probably won't.