X0202 4 2007-10-19 0000073124 NORTHERN TRUST CORP NTRS 0001378549 Potter Stephen N 50 S. LA SALLE ST. CHICAGO IL 60603 0 1 0 0 Executive Vice President Common Stock 2007-10-19 4 F 0 1578 69.45 D 15188 D Common Stock 36395 I By Trust Common Stock 8292 I 401(k) Common Stock 880 I Spouse as Trustee for Daughter Common Stock 880 I Spouse as Trustee for Son Represents stock units payable automatically on a 1-for-1 basis in shares of the Corporation's common stock. Represents stock units withheld to pay taxes on the distribution of 4,000 stock units. Total represents the distribution of 4,000 stock units. Includes 2,422 shares of common stock (net of taxes) received upon the distribution of already-reported stock units. as of 9/30/2007 Eileen C. Ratzka attorney-in-fact for Stephen N. Potter 2007-10-23