|   |   | I have reviewed this Quarterly      Report on Form 10-Q of the MacroShares Major      Metro Housing Down  Trust; |
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|   |   | 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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|   |   | 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 thisreport; |
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|   |   | 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, 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 period (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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|   |   | 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 MacroShares Housing Depositor, LLC, 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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|   | By:   | /s/ Samuel Masucci,      III                                                                   |
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|   |            | Samuel Masucci,      IIIChief Executive Officer of      Depositor,on behalf of      Registrant |

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