{
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  "stock_code": "1820",
  "company_name": "西松建設",
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  "updated": "2026-08-17",
  "license": "© 2026 Yutaka Sugiura. All rights reserved.",
  "attribution": "The社史 (the-shashi.com) — https://the-shashi.com/tse/1820/",
  "source": {
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      "有価証券報告書",
      "公式サイト沿革",
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    {
      "date": "1874",
      "importance": 3,
      "event": "西松桂輔が美濃国安八郡（現・岐阜県）で土木請負業を創業",
      "source": "公式サイト沿革"
    },
    {
      "date": "1916",
      "importance": 1,
      "event": "西松組に商号変更",
      "source": "公式サイト沿革"
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    {
      "date": "1937/9",
      "importance": 2,
      "event": "西松組を設立",
      "source": "有価証券報告書"
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    {
      "date": "1948/7",
      "importance": 2,
      "event": "西松建設に商号変更",
      "source": "有価証券報告書"
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    {
      "date": "1950/6",
      "importance": 1,
      "event": "技術研究所を開設",
      "source": "有価証券報告書"
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    {
      "date": "1957/10",
      "importance": 1,
      "event": "多摩川工場を開設",
      "source": "有価証券報告書"
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    {
      "date": "1961/2",
      "importance": 1,
      "event": "松栄不動産を設立",
      "source": "有価証券報告書"
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    {
      "date": "1961/11",
      "importance": 1,
      "event": "東京証券取引所第二部に上場",
      "source": "有価証券報告書"
    },
    {
      "date": "1962/8",
      "importance": 1,
      "event": "本社新社屋が完成",
      "source": "公式サイト沿革"
    },
    {
      "date": "1963/8",
      "importance": 1,
      "event": "東京証券取引所第一部に上場",
      "source": "有価証券報告書"
    },
    {
      "date": "1965/6",
      "importance": 1,
      "event": "香港支店を開設",
      "source": "有価証券報告書"
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    {
      "date": "1965/10",
      "importance": 1,
      "event": "多摩川工場を移転し平塚製作所を開設",
      "source": "有価証券報告書"
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    {
      "date": "1998/1",
      "importance": 1,
      "event": "愛川衝撃振動研究所（神奈川県愛甲郡）を開設",
      "source": "有価証券報告書"
    },
    {
      "date": "2009",
      "importance": 3,
      "event": "元社長が外為法違反と政治資金規正法違反で起訴、国土交通省等から指名停止処分",
      "source": "有価証券報告書"
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    {
      "date": "2009/6",
      "importance": 2,
      "event": "近藤晴貞が代表取締役社長に就任",
      "source": "有価証券報告書"
    },
    {
      "date": "2010/3",
      "importance": 1,
      "event": "西松地所を設立",
      "source": "有価証券報告書"
    },
    {
      "date": "2010/6",
      "importance": 1,
      "event": "松栄不動産を吸収合併",
      "source": "有価証券報告書"
    },
    {
      "date": "2016/6",
      "importance": 1,
      "event": "監査等委員会設置会社に移行",
      "source": "有価証券報告書"
    },
    {
      "date": "2018/4",
      "importance": 2,
      "event": "髙瀨伸利が代表取締役社長に就任",
      "source": "有価証券報告書"
    },
    {
      "date": "2021/3",
      "importance": 2,
      "event": "シティインデックスイレブンスが持株比率9.94％で筆頭株主",
      "source": "有価証券報告書"
    },
    {
      "date": "2021/12",
      "importance": 3,
      "event": "伊藤忠商事と資本業務提携を締結",
      "source": "IR"
    },
    {
      "date": "2022/4",
      "importance": 1,
      "event": "東京証券取引所プライム市場へ移行",
      "source": "有価証券報告書"
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    {
      "date": "2024/6",
      "importance": 2,
      "event": "細川雅一が代表取締役社長に就任",
      "source": "有価証券報告書"
    }
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}