Source : Webster's Revised Unabridged Dictionary (1913)

Top out \Top out\ (Building)
   To top off; to finish by putting on a cap of top (uppermost)
   course (called a

   {top`ping-out" course}).

Source : WordNet®

top out
     v 1: give up one's career just as one becomes very successful;
          "The financial consultant topped out at age 40 because
          he was burned out"
     2: reach the highest point; "Bids for the painting topped out
        at $50 million" [ant: {bottom out}]