preemptive
pre.emp.tive \-'em(p)-tiv\ aj 1: of or relating to preemption : having
power to preempt 2: of a bid in bridge that is higher than necessary and
designed to shut o ut bids by the opponents giving a stockholder first
option to purchase new stock in an amount proportionate to his existing
holdings {~ right} - pre.emp.tive.ly av
Webster's English Dictionary