I was watching the match close today (Nov 24). At 4:02 pm there were 2 sellers for 578 shares and 49.5 and a buyer for 578 at the 51.5 (which incidentally was the prevailing price) - match at 51.5!
At 4:05 another seller can in with 2 shares at 49.5 which forced the match down to 51.... 2 shares!!
RXP in the last 8 trading days; 5 down, 1 up price 10.5% down - go figure!!