RYDEX ETF TRUST 9601 BLACKWELL ROAD, SUITE 500 ROCKVILLE, MD 20850 March 1, 2006 State Street Bank and Trust Company 150 Newport Avenue, 4th floor Quincy, Massachusetts 02171 Attention: Michael E. Prendergast, Vice President Ladies and Gentlemen:...

                                 RYDEX ETF TRUST
                         0000 XXXXXXXXX XXXX, XXXXX 000
                               XXXXXXXXX, XX 00000

March 1, 0000

Xxxxx Xxxxxx Xxxx and Trust Company
000 Xxxxxxx Xxxxxx, 0xx xxxxx
Xxxxxx, Xxxxxxxxxxxxx 00000
Attention: Xxxxxxx X. Xxxxxxxxxxx, Vice President

Ladies and Gentlemen:

      Reference is made to the Custodian  Agreement between Rydex ETF Trust (the
"Fund") and State Street Bank and Trust Company ("State Street") dated as of May
3, 2005, including Appendix A thereto (as amended, the "Agreement").

      Pursuant  to  Section  18.6 of the  Agreement,  this  letter is to provide
written  notice to State  Street of the Fund's  desire to include the  following
series ("Additional Series") as additional Portfolios under the Agreement:

                  Rydex S&P 500 Pure Value ETF
                  Rydex S&P 500 Pure Growth ETF
                  Rydex S&P MidCap 400 Pure Value ETF
                  Rydex S&P MidCap 400 Pure Growth ETF
                  Rydex S&P SmallCap 600 Pure Value ETF
                  Rydex S&P SmallCap 600 Pure Growth ETF

      In accordance with the such section,  we request that State Street confirm
that it will render services as custodian with respect to the Additional  Series
and that  Appendix A to the  Agreement  be amended in its  entirety and replaced
with a new Appendix A annexed hereto.

                            [Signature page follows.]



Please indicate your acceptance of the foregoing by executing two copies of this
Agreement, returning one to the Fund and retaining one copy for your records.

                                 Very truly yours,

                                 RYDEX ETF TRUST


                                 By:       /s/ Xxxx Xxxxx
                                           -------------------------------------
                                 Name:     Xxxx Xxxxx
                                 Title:    Vice President and Treasurer

                                 Accepted:

                                 STATE STREET BANK AND TRUST COMPANY


                                 By:       /s/ Xxxxxx X. Xxxxxx
                                           -------------------------------------
                                 Name:     Xxxxxx X. Xxxxxx
                                 Title:    Executive Vice President



                                   APPENDIX A
                    To Custodian Agreement dated May 3, 2005

                          Effective as of Xxxxx 0, 0000

          XXXXX XXXXXXX TOP 50 ETF
          RYDEX S&P EQUAL WEIGHT ETF
          RYDEX S&P 500 PURE VALUE ETF
          RYDEX S&P 500 PURE GROWTH ETF
          RYDEX S&P MIDCAP 400 PURE VALUE ETF
          RYDEX S&P MIDCAP 400 PURE GROWTH ETF
          RYDEX S&P SMALLCAP 600 PURE VALUE ETF
          RYDEX S&P SMALLCAP 600 PURE GROWTH ETF