AMENDMENT NO. 1 TO RIGHTS AGREEMENT

This Amendment No. 1 (this “Amendment”), is entered into as of August 13, 2013, to amend that certain Rights Agreement, dated as of August 31, 2012 (the “Rights Agreement”), between A. M. Castle & Co., a Maryland corporation (the “Company”), and American Stock Transfer & Trust Company, LLC, a limited liability trust company organized under the laws of the State of New York (the “Rights Agent”).

WHEREAS, on August 13, the Board of Directors of the Company (the “Board”) determined it is in the best interests of the Company and its stockholders to amend the Rights Agreement on the terms set forth herein; and

WHEREAS, in accordance with Section 27 of the Rights Agreement, the Company, by action of the Board, may from time to time supplement or amend the Rights Agreement in a writing signed by the Company and the Rights Agent.

NOW, THEREFORE, the Company and the Rights Agent agree as follows:

1.Section 7(a) of the Rights Agreement is hereby amended and restated in its entirety as follows:

(a) Subject to Sections 7(e) and 9(c) hereof, prior to (i) the Close of Business on August 30, 2014 (the “Final Expiration Date”), or (ii) the time at which the Rights are redeemed as provided in Section 23 hereof or (iii) the time at which the Rights are exchanged as provided in Section 11(c) hereof (the earlier of (i), (ii), and (iii) being the “Expiration Date”), the registered holder of any Right Certificate may exercise the Rights evidenced thereby in whole or in part at any time after the Distribution Date (except as provided herein) upon surrender of the Right Certificate, with the form of election to purchase on the reverse side thereof duly executed, to the Rights Agent at the principal corporate trust office of the Rights Agent, together with payment of the Purchase Price for each share of Preferred Stock as to which the Rights are exercised.