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    <submissionType>13F-HR/A</submissionType>
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      <liveTestFlag>LIVE</liveTestFlag>
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        <confirmingCopyFlag>false</confirmingCopyFlag>
        <returnCopyFlag>false</returnCopyFlag>
        <overrideInternetFlag>false</overrideInternetFlag>
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      <filer>
        <credentials>
          <cik>0001320168</cik>
          <ccc>XXXXXXXX</ccc>
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      <periodOfReport>09-30-2017</periodOfReport>
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      <reportCalendarOrQuarter>09-30-2017</reportCalendarOrQuarter>
      <isAmendment>true</isAmendment>
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      <amendmentInfo>
        <amendmentType>RESTATEMENT</amendmentType>
        <confDeniedExpired>false</confDeniedExpired>
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      <filingManager>
        <name>AMERICAN CAPITAL MANAGEMENT INC</name>
        <address>
          <ns1:street1>551 Madison Avenue</ns1:street1>
          <ns1:street2>Suite 902</ns1:street2>
          <ns1:city>New York</ns1:city>
          <ns1:stateOrCountry>NY</ns1:stateOrCountry>
          <ns1:zipCode>10022</ns1:zipCode>
        </address>
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      <reportType>13F HOLDINGS REPORT</reportType>
      <form13FFileNumber>028-11313</form13FFileNumber>
      <provideInfoForInstruction5>N</provideInfoForInstruction5>
    </coverPage>
    <signatureBlock>
      <name>Arlene Francis</name>
      <title>Office Manager</title>
      <phone>212-344-3300</phone>
      <signature>/s/ Arlene Francis</signature>
      <city>New York</city>
      <stateOrCountry>NY</stateOrCountry>
      <signatureDate>04-04-2018</signatureDate>
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