{
 "company": "aecom",
 "ticker": "ACM",
 "cusip": "00766T100",
 "security": "Common stock",
 "as_of_13f_period": "2026-06-30",
 "generated": "2026-10-31",
 "source": "SEC Form 13F data sets (13F-HR, share positions only; options excluded), https://www.sec.gov/data-research/sec-markets-data/form-13f-data-sets; shares outstanding from 10-Q/10-K cover pages.",
 "excluded_positions": [
  {
   "co": "aecom",
   "period": "2026-06-30",
   "manager": "Sixth Street Partners Management Company, L.P.",
   "shares": 968695
  },
  {
   "co": "aecom",
   "period": "2024-03-31",
   "manager": "PAYDEN & RYGEL INVESTMENT GROUP",
   "shares": 159470
  },
  {
   "co": "aecom",
   "period": "2023-09-30",
   "manager": "PAYDEN & RYGEL INVESTMENT GROUP",
   "shares": 297070
  }
 ],
 "method": "Institutional % = shares reported on 13F-HR filings for the quarter (latest original or restated filing per manager, plus new-holdings amendments) divided by shares outstanding on the next cover page. 13F totals can double-count where parent and subsidiary managers both report, and exclude non-13F holders. Totals can exceed 100% of shares outstanding, mainly because shares lent to short sellers are reported both by the lending institution and by the buyer.",
 "quarters": [
  {
   "period": "2024-09-30",
   "filers": 524,
   "inst_shares": 115482510,
   "shares_out": 132463704,
   "shares_out_date": "2024-11-15",
   "shares_out_basis": "Common shares outstanding",
   "inst_pct": 87.2
  },
  {
   "period": "2024-12-31",
   "filers": 571,
   "inst_shares": 116198461,
   "shares_out": 132689650,
   "shares_out_date": "2025-01-31",
   "shares_out_basis": "Common shares outstanding",
   "inst_pct": 87.6
  },
  {
   "period": "2025-03-31",
   "filers": 572,
   "inst_shares": 115609753,
   "shares_out": 132300603,
   "shares_out_date": "2025-05-02",
   "shares_out_basis": "Common shares outstanding",
   "inst_pct": 87.4
  },
  {
   "period": "2025-06-30",
   "filers": 635,
   "inst_shares": 118650580,
   "shares_out": 132446101,
   "shares_out_date": "2025-07-31",
   "shares_out_basis": "Common shares outstanding",
   "inst_pct": 89.6
  },
  {
   "period": "2025-09-30",
   "filers": 642,
   "inst_shares": 118096861,
   "shares_out": 131833332,
   "shares_out_date": "2025-11-14",
   "shares_out_basis": "Common shares outstanding",
   "inst_pct": 89.6
  },
  {
   "period": "2025-12-31",
   "filers": 646,
   "inst_shares": 115959754,
   "shares_out": 129288624,
   "shares_out_date": "2026-02-06",
   "shares_out_basis": "Common shares outstanding",
   "inst_pct": 89.7
  },
  {
   "period": "2026-03-31",
   "filers": 619,
   "inst_shares": 113638993,
   "shares_out": 128522920,
   "shares_out_date": "2026-05-08",
   "shares_out_basis": "Common shares outstanding",
   "inst_pct": 88.4
  },
  {
   "period": "2026-06-30",
   "filers": 569,
   "inst_shares": 119579869,
   "shares_out": 128696425,
   "shares_out_date": "2026-08-07",
   "shares_out_basis": "Common shares outstanding",
   "inst_pct": 92.9
  }
 ],
 "top_holders": [
  {
   "manager": "BlackRock, Inc.",
   "filer_cik": "0002012383",
   "shares": 14379638,
   "pct": 11.17,
   "change_shares": -1380726
  },
  {
   "manager": "Vanguard (all 13F filers)",
   "filer_cik": "fam:VANGUARD",
   "shares": 12305811,
   "pct": 9.56,
   "change_shares": 21698
  },
  {
   "manager": "Primecap Management Co/ca/",
   "filer_cik": "0000763212",
   "shares": 8787043,
   "pct": 6.83,
   "change_shares": 139970
  },
  {
   "manager": "Barrow Hanley Mewhinney & Strauss LLC",
   "filer_cik": "0000313028",
   "shares": 5497153,
   "pct": 4.27,
   "change_shares": 2644431
  },
  {
   "manager": "State Street Corp.",
   "filer_cik": "0000093751",
   "shares": 4106098,
   "pct": 3.19,
   "change_shares": -935362
  },
  {
   "manager": "FMR LLC",
   "filer_cik": "0000315066",
   "shares": 3758192,
   "pct": 2.92,
   "change_shares": 1650112
  },
  {
   "manager": "UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC",
   "filer_cik": "0000861177",
   "shares": 3565323,
   "pct": 2.77,
   "change_shares": 83360
  },
  {
   "manager": "Invesco Ltd.",
   "filer_cik": "0000914208",
   "shares": 3191873,
   "pct": 2.48,
   "change_shares": -383478
  },
  {
   "manager": "First Trust Advisors LP",
   "filer_cik": "0001125816",
   "shares": 2446092,
   "pct": 1.9,
   "change_shares": -580354
  },
  {
   "manager": "Geode Capital Management, LLC",
   "filer_cik": "0001214717",
   "shares": 2445738,
   "pct": 1.9,
   "change_shares": -23711
  }
 ],
 "top_holders_trend": {
  "periods": [
   "2024-09-30",
   "2024-12-31",
   "2025-03-31",
   "2025-06-30",
   "2025-09-30",
   "2025-12-31",
   "2026-03-31",
   "2026-06-30"
  ],
  "holders": [
   {
    "manager": "BlackRock, Inc.",
    "filer_cik": "0002012383",
    "pct": [
     11.93,
     11.79,
     11.33,
     11.54,
     11.14,
     11.76,
     12.26,
     11.17
    ]
   },
   {
    "manager": "Vanguard (all 13F filers)",
    "filer_cik": "fam:VANGUARD",
    "pct": [
     9.74,
     9.66,
     9.63,
     9.53,
     9.5,
     9.51,
     9.56,
     9.56
    ]
   },
   {
    "manager": "Primecap Management Co/ca/",
    "filer_cik": "0000763212",
    "pct": [
     9.45,
     8.58,
     7.67,
     7.22,
     6.73,
     6.7,
     6.73,
     6.83
    ]
   },
   {
    "manager": "Barrow Hanley Mewhinney & Strauss LLC",
    "filer_cik": "0000313028",
    "pct": [
     1.73,
     1.66,
     1.49,
     1.66,
     1.68,
     1.52,
     2.22,
     4.27
    ]
   },
   {
    "manager": "State Street Corp.",
    "filer_cik": "0000093751",
    "pct": [
     3.78,
     3.87,
     3.92,
     3.76,
     3.87,
     3.9,
     3.92,
     3.19
    ]
   }
  ]
 },
 "grouping": "Vanguard’s separate 13F filers (The Vanguard Group; from 2026, Vanguard Capital Management and Vanguard Portfolio Management) are combined; other managers are shown per 13F filer.",
 "insiders": {
  "class": "Common stock",
  "rows": [
   {
    "proxy_filed": "2024-01-29",
    "group": "All directors and executive officers (12)",
    "shares": 572173,
    "pct_reported": "<1%",
    "url": "https://www.sec.gov/Archives/edgar/data/868857/000110465924007786/tm2325194d4_def14a.htm",
    "doc": "Proxy statement (DEF 14A)",
    "pct_value": 0.42,
    "pct_basis": "computed: proxy share count ÷ common shares outstanding as of 2024-02-01"
   },
   {
    "proxy_filed": "2025-01-17",
    "group": "All directors and executive officers (12)",
    "shares": 539405,
    "pct_reported": "<1%",
    "url": "https://www.sec.gov/Archives/edgar/data/868857/000162828025001826/acm-20250117.htm",
    "doc": "Proxy statement (DEF 14A)",
    "pct_value": 0.41,
    "pct_basis": "computed: proxy share count ÷ common shares outstanding as of 2025-01-31"
   },
   {
    "proxy_filed": "2026-01-20",
    "group": "All directors and executive officers (11)",
    "shares": 591308,
    "pct_reported": "<1%",
    "url": "https://www.sec.gov/Archives/edgar/data/868857/000086885726000006/acm-20260119.htm",
    "doc": "Proxy statement (DEF 14A)",
    "pct_value": 0.46,
    "pct_basis": "computed: proxy share count ÷ common shares outstanding as of 2026-02-06"
   }
  ]
 }
}