this will ultimately depend if the new company came to you or if you went to the new company. If they want you they probably have an acquisition price in mind

this will ultimately depend if the new company came to you or if you went to the new company. If they want you they probably have an acquisition price in mind i.e salary + benefits but you are in a decent bargaining position for any potential losses. If you have gone to them then I am not sure they would really entertain the idea. If they did agree to discuss it you may want to consider asking for a like for like compensation in the event you do lose your options/bonus etc, as you dont know what exactly you would lose until you tell your current firm you are leaving.