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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>SEC FORM 
            4</title><style type="text/css">
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      </style></head><body>SEC Form 4 
   <table width="100%" border="0" cellspacing="0" cellpadding="4"><tr><td width="20%" colspan="2" valign="top" align="center" class="FormName">FORM 4</td><td rowspan="2" width="60%" valign="middle" align="center"><span class="FormTitle">UNITED STATES SECURITIES AND EXCHANGE COMMISSION</span><br><span class="MedSmallFormText">Washington, D.C. 20549</span><br><br><span class="FormTitle">STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP</span><br><br><span class="MedSmallFormText">Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934</span><br><span class="MedSmallFormText">or Section 30(h) of the Investment Company Act of 1940</span></td><td rowspan="2" width="20%" valign="top" align="center"><table width="100%" border="1" summary="OMB Approval Status Box"><tr><td class="FormTextC">OMB APPROVAL</td></tr><tr><td><table width="100%" border="0" summary="OMB Interior Box"><tr><td class="SmallFormText" colspan="3">OMB Number:</td><td class="SmallFormTextR">3235-0287</td></tr><tr><td class="SmallFormText" colspan="4">Estimated average burden</td></tr><tr><td class="SmallFormText" colspan="3">hours per response:</td><td class="SmallFormTextR">0.5</td></tr></table></td></tr></table></td></tr><tr valign="middle"><td><table width="100%" border="1" cellpadding="0" cellspacing="0"><tr><td>  </td></tr></table></td><td class="SmallFormText">Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. 
         <i>See</i>

         Instruction 1(b).</td></tr><tr valign="middle"><td><table width="100%" border="1" cellpadding="0" cellspacing="0"><tr><td>  </td></tr></table></td><td class="SmallFormText">Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10. </td></tr></table><table width="100%" border="1" cellspacing="0" cellpadding="4"><tr><td rowspan="4" width="35%" valign="top"><span class="MedSmallFormText">1. Name and Address of Reporting Person<sup>*</sup></span><table border="0" width="100%"><tr><td><a href="/cgi-bin/browse-edgar?action=getcompany&amp;CIK=0001688276">Samuels Theodore R. II</a></td></tr></table><hr width="98%"><table border="0" width="100%"><tr><td width="33%" class="MedSmallFormText">(Last)</td><td width="33%" class="MedSmallFormText">(First)</td><td width="33%" class="MedSmallFormText">(Middle)</td></tr></table><table border="0" width="100%"><tr><td><span class="FormData">C/O IRON MOUNTAIN INCORPORATED</span></td></tr><tr><td><span class="FormData">85 NEW HAMPSHIRE AVENUE, SUITE 150</span></td></tr></table><hr width="98%"><span class="MedSmallFormText">(Street)</span><table border="0" width="100%"><tr><td width="33%"><span class="FormData">PORTSMOUTH</span></td><td width="33%"><span class="FormData">
				NEW HAMPSHIRE
			</span></td><td width="33%"><span class="FormData">03801</span></td></tr></table><hr width="98%"><table border="0" width="100%"><tr><td width="33%" class="MedSmallFormText">(City)</td><td width="33%" class="MedSmallFormText">(State)</td><td width="33%" class="MedSmallFormText">(Zip)</td></tr></table><hr width="98%"><table border="0" width="100%"><tr><td width="33%" colspen="3"><span class="FormData">UNITED STATES</span></td></tr></table><hr width="98%"><span class="MedSmallFormText">(Country)</span></td><td width="35%" valign="top"><span class="MedSmallFormText">2. Issuer Name <b>and</b> Ticker or Trading Symbol
      </span><br><a href="/cgi-bin/browse-edgar?action=getcompany&amp;CIK=0001020569">IRON MOUNTAIN INC</a>
     [ <span class="FormData">IRM</span> ]
   </td><td rowspan="2" valign="top"><span class="MedSmallFormText">5. Relationship of Reporting Person(s) to Issuer
      </span><br><span class="MedSmallFormText">(Check all applicable)</span><table border="0" width="100%"><tr><td width="15%" align="center"><span class="FormData">X</span></td><td width="35%" class="MedSmallFormText">Director</td><td width="15%" align="center"></td><td width="35%" class="MedSmallFormText">10% Owner</td></tr><tr><td align="center"></td><td class="MedSmallFormText">Officer (give title below)</td><td align="center"></td><td class="MedSmallFormText">Other (specify below)</td></tr><tr><td width="15%" align="center"></td><td width="35%" align="left" style="color: blue"></td><td width="15%" align="center"></td><td width="35%" align="left" style="color: blue"></td></tr></table></td></tr><tr><td valign="top"><span class="MedSmallFormText">2a. Foreign Trading Symbol
		 <br></span></td></tr><tr><td valign="top"><span class="MedSmallFormText">3. Date of Earliest Transaction
         (Month/Day/Year)</span><br><span class="FormData">07/02/2026</span></td><td valign="top" rowspan="2"><span class="MedSmallFormText">6. Individual or Joint/Group Filing (Check Applicable Line)
      </span><table border="0" width="100%"><tr><td width="15%" align="center"><span class="FormData">X</span></td><td width="85%" class="MedSmallFormText">Form filed by One Reporting Person</td></tr><tr><td width="15%" align="center"></td><td width="85%" class="MedSmallFormText">Form filed by More than One Reporting Person</td></tr></table></td></tr><tr><td valign="top" rowspan="1"><span class="MedSmallFormText">4. If Amendment, Date of Original Filed
         (Month/Day/Year)</span><br><br></td></tr></table><table width="100%" border="1" cellspacing="0" cellpadding="4"><thead><tr><th width="100%" valign="top" colspan="11" align="center" class="FormTextC"><b>Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned</b></th></tr><tr><th width="36%" valign="top" rowspan="2" align="left" class="MedSmallFormText">1. Title of Security (Instr. 
      3)
   </th><th width="6%" valign="top" rowspan="2" align="left" class="SmallFormText">2. Transaction Date
      (Month/Day/Year)</th><th width="5%" valign="top" rowspan="2" align="left" class="SmallFormText">2A. Deemed Execution Date, if any
      (Month/Day/Year)</th><th width="7%" valign="top" colspan="2" align="left" class="SmallFormText">3. Transaction Code (Instr. 
      8)
   </th><th width="19%" valign="top" colspan="3" align="left" class="SmallFormText">4. Securities Acquired (A) or Disposed Of (D) (Instr. 
      3, 4 and 5)
   </th><th width="11%" valign="top" rowspan="2" align="left" class="SmallFormText">5. 
      Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 
      3 and 4)
   </th><th width="9%" valign="top" rowspan="2" align="left" class="SmallFormText">6. Ownership Form: Direct (D) or Indirect (I) (Instr. 
      4)
   </th><th width="8%" valign="top" rowspan="2" align="left" class="SmallFormText">7. Nature of Indirect Beneficial Ownership (Instr. 
      4)
   </th></tr><tr><th width="4%" align="center" class="SmallFormText">Code</th><th width="3%" align="center" class="SmallFormText">V</th><th width="8%" align="center" class="SmallFormText">Amount</th><th width="5%" align="center" class="SmallFormText">(A) or (D)</th><th width="6%" align="center" class="SmallFormText">Price</th></tr></thead></table><table width="100%" border="1" cellspacing="0" cellpadding="4"><thead><tr><th width="100%" valign="top" colspan="16" align="center" class="FormTextC"><b>Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned</b><br><b>(e.g., puts, calls, warrants, options, convertible securities)</b></th></tr><tr><th width="13%" valign="top" rowspan="2" align="left" class="SmallFormText">1. Title of Derivative Security (Instr. 
      3)
   </th><th width="5%" valign="top" rowspan="2" align="left" class="SmallFormText">2. Conversion or Exercise Price of Derivative Security
   </th><th width="5%" valign="top" rowspan="2" align="left" class="SmallFormText">3. Transaction Date
      (Month/Day/Year)</th><th width="5%" valign="top" rowspan="2" align="left" class="SmallFormText">3A. Deemed Execution Date, if any
      (Month/Day/Year)</th><th width="9%" valign="top" colspan="2" align="left" class="SmallFormText">4. Transaction Code (Instr. 
      8)
   </th><th width="10%" valign="top" colspan="2" align="left" class="SmallFormText">5. 
      Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 
      3, 4 and 5)
   </th><th width="9%" valign="top" colspan="2" align="left" class="SmallFormText">6. Date Exercisable and Expiration Date 
      (Month/Day/Year)</th><th width="17%" valign="top" colspan="2" align="left" class="SmallFormText">7. Title and Amount of Securities Underlying Derivative Security (Instr. 
      3 and 4)
   </th><th width="6%" valign="top" rowspan="2" align="left" class="SmallFormText">8. Price of Derivative Security (Instr. 
      5)
   </th><th width="6%" valign="top" rowspan="2" align="left" class="SmallFormText">9. 
      Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 
      4)
   </th><th width="6%" valign="top" rowspan="2" align="left" class="SmallFormText">10. Ownership Form: Direct (D) or Indirect (I) (Instr. 
      4)
   </th><th width="7%" valign="top" rowspan="2" align="left" class="SmallFormText">11. Nature of Indirect Beneficial Ownership (Instr. 
      4)
   </th></tr><tr><th width="4%" valign="bottom" align="center" class="SmallFormText">Code</th><th width="4%" valign="bottom" align="center" class="SmallFormText">V</th><th width="5%" valign="bottom" align="center" class="SmallFormText">(A)</th><th width="5%" valign="bottom" align="center" class="SmallFormText">(D)</th><th width="5%" valign="bottom" align="center" class="SmallFormText">Date Exercisable</th><th width="4%" valign="bottom" align="center" class="SmallFormText">Expiration Date</th><th width="10%" valign="bottom" align="center" class="SmallFormText">Title</th><th width="7%" valign="bottom" align="center" class="SmallFormText">Amount or Number of Shares</th></tr></thead><tbody><tr><td align="left"><span class="SmallFormData">Phantom Stock</span></td><td align="center"><span class="FootnoteData"><sup>(1)</sup></span></td><td align="center"><span class="SmallFormData">07/02/2026</span></td><td align="center"></td><td align="center"><span class="SmallFormData">A</span></td><td align="center"></td><td align="center"><span class="SmallFormData">310.86</span><span class="FootnoteData"><sup>(2)</sup></span></td><td align="center"></td><td align="center"><span class="SmallFormData">
                
            </span><span class="FootnoteData"><sup>(1)</sup></span></td><td align="center"><span class="SmallFormData">
                
            </span><span class="FootnoteData"><sup>(1)</sup></span></td><td align="center"><span class="SmallFormData">Common Stock</span></td><td align="center"><span class="FormData">310.86</span></td><td align="center"><span class="SmallFormText">$</span><span class="SmallFormData">116.61</span></td><td align="center"><span class="SmallFormData">13,701.27</span></td><td align="center"><span class="SmallFormData">D</span></td><td align="left"></td></tr></tbody></table><table border="0" width="100%"><tr><td class="MedSmallFormText"><b>Explanation of Responses:</b></td></tr><tr><td class="FootnoteData">1. Pursuant to the Reporting Person's election to participate in the Iron Mountain Incorporated Directors Deferred Compensation Plan, the shares of phantom stock (the "Phantom Shares") will become payable in shares of Iron Mountain Incorporated common stock ("Common Stock") following the Reporting Person's disability or cessation of service as a director. Each Phantom Share is the economic equivalent of one share of Common Stock.</td></tr><tr><td class="FootnoteData">2. These shares give effect to the Reporting Person's quarterly cash compensation for services on the board of directors of the Company as if reinvested in Phantom Shares.</td></tr><tr><td class="FormText"><b>Remarks:</b></td></tr><tr><td class="FootnoteData"></td></tr></table><table width="100%" border="0"><tr><td width="60%"></td><td width="20%"><u><span class="FormData">/s/ Keely Stewart, under Power of Attorney dated July 6, 2023 from Theodore R Samuels</span></u></td><td width="20%"><u><span class="FormData">07/06/2026</span></u></td></tr><tr><td></td><td class="MedSmallFormText">** Signature of Reporting Person</td><td class="MedSmallFormText">Date</td></tr><tr><td colspan="3" class="MedSmallFormText">Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.</td></tr><tr><td colspan="3" class="MedSmallFormText">* If the form is filed by more than one reporting person, 
                  <i>see</i>

                  Instruction 
                  4

                  (b)(v).</td></tr><tr><td colspan="3" class="MedSmallFormText">** Intentional misstatements or omissions of facts constitute Federal Criminal Violations 
                  <i>See</i>

                  18 U.S.C. 1001 and 15 U.S.C. 78ff(a).</td></tr><tr><td colspan="3" class="MedSmallFormText">Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, 
                  <i>see</i>

                  Instruction 6 for procedure.</td></tr><tr><td colspan="3" class="MedSmallFormText"><b>Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.</b></td></tr><tr><td colspan="3" class="MedSmallFormText"><b>* Form 4: SEC 1474 (03-26)</b></td></tr></table></body></html>
