**Exhibit      31.1**

**CERTIFICATION      PURSUANT TO**

**SECTION      302(a) OF THE SARBANES-OXLEY ACT OF 2002**

| 1. | I have reviewed this Annual              Report              on Form 10-K of the Claymore MACROshares Oil Down Holding              Trust; |
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| 2. | Based on my knowledge,                this report                does not contain any untrue statement of a material fact or omit                to state                a material fact necessary to make the statements made, in light of                the                circumstances under which such statements were made, not misleading                with                respect to the period covered by this                report; |
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| 3. | Based on my knowledge,                    the                    financial statements, and other financial information included                    in this                    report, fairly present in all material respects the financial                    condition,                    results of operations and cash flows of the registrant as of,                    and for, the                    periods presented in this report; |
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| 4. | The other certifying                        officer(s) and                        I are responsible for establishing and maintaining disclosure                        controls and                        procedures (as defined in Exchange Act Rules 13a-15(e) and                        15d-15(e)) for                        the registrant and                        have: |
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|   | a. | Designed                such disclosure controls and procedures, or caused such disclosure                controls and procedures to be designed under our supervision, to                ensure                that material information relating to the registrant, including its                consolidated subsidiaries, is made known to us by others within those                entities, particularly during the period in which this report is                being                prepared; |
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|   | b. | Evaluated                the effectiveness of the registrant's disclosure controls and procedures                and presented in this report our conclusions about the effectiveness                of                the disclosure controls and procedures, as of the end of the period                covered by this report based on such evaluation;                and |
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|   | c. | Disclosed                in this report any change in the registrant's internal control over                financial reporting that occurred during the registrant's most recent                fiscal quarter (the registrant's fourth fiscal quarter in the case                of an                annual report) that has materially affected, or is reasonably likely                to                materially affect, the registrant's internal control over financial                reporting; and |
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| 5. | The other certifying                  officer(s) and                  I have disclosed, based on our most recent evaluation of internal                  control                  over financial reporting, to the registrant's auditors, the board                  of                  managers of Macro Securities Depositor, LLC, the audit committee                  of                  Claymore Securities, Inc., Claymore Securities, Inc.'s auditors                  and the                  audit committee of MacroMarkets LLC (or persons performing the                  equivalent                  functions): |
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|   | a. | All                significant deficiencies and material weaknesses in the design or                operation of internal control over financial reporting which are                reasonably likely to adversely affect the registrant's ability to                record,                process, summarize and report financial information;                and |
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|   | b. | Any                fraud, whether or not material, that involves persons who have a                significant role in the registrant's internal control over financial                reporting. |
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|   |                                                                         | /s/ Samuel                    Masucci, III |
|   | Samuel                    Masucci, III                                       |
|   | Chief Executive Officer,MACRO Securities Depositor,                      LLC |

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