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Institutional Ownership · SEC Form 13F

Who owns ATO (ATO)


Which tracked institutional funds hold ATO, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See ATO company fundamentals →

Ownership as of the 2026-Q1 13F filings. 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.

1,020
Institutional holders
158,852,890
Shares held (tracked funds)
98.3%
Of shares outstanding

How the tape is positioned

The tracked-fund tape on ATO is one-sided between 2025-Q4 and 2026-Q1: 334 added or opened and 112 trimmed or exited — on balance accumulating.

A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.

Conviction spread

ATO’s largest tracked holder by dollar value, VANGUARD GROUP INC, sizes it at 0.1% of its own reported 13F book, while the median holder sizes it at 0.1% of theirs — a 0.0pp gap the other way — the median holder sizes ATO more heavily than its largest holder by dollar value does.

Book-share is each fund’s reported value in ATO divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.

Institutional & insider positioning

Between 2025-Q4 and 2026-Q1, across 1015 tracked filers holding ATO, 544 increased or opened the position and 419 reduced or closed it; over the same quarter, there were no open-market insider Form 4s.

This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.

New buyers & exits

Funds opening or closing a position in ATO between the 2025-Q4 and 2026-Q1 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.

New buyers 48

  • VANGUARD CAPITAL MANAGEMENT LLC$2.0B
  • VANGUARD PORTFOLIO MANAGEMENT LLC$1.7B
  • Capital Research Global Investors$741M
  • VANGUARD FIDUCIARY TRUST CO$172M
  • Vanguard Global Advisers, LLC$67M
  • VANGUARD ASSET MANAGEMENT, Ltd$56M

Full exits 44

  • VANGUARD GROUP INC$3.5B
  • Pacer Advisors, Inc.$46M
  • MIZUHO MARKETS AMERICAS LLC$40M
  • Skandinaviska Enskilda Banken AB (publ)$24M
  • SUSQUEHANNA FUNDAMENTAL INVESTMENTS, LLC$13M
  • D. E. Shaw & Co., Inc.$12M

Largest adds

  • STATE STREET CORP$293M
  • GOLDMAN SACHS GROUP INC$149M
  • BANK OF AMERICA CORP /DE/$142M
  • WELLINGTON MANAGEMENT GROUP LLP$105M
  • BNP PARIBAS FINANCIAL MARKETS$101M
  • Amundi$95M

Largest trims

  • Capital International Investors$640M
  • PRICE T ROWE ASSOCIATES INC /MD/$604M
  • Aristotle Capital Management, LLC$169M
  • BlackRock, Inc.$160M
  • NORGES BANK$110M
  • NORTHWESTERN MUTUAL WEALTH MANAGEMENT CO$108M

Institutional holders

One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).

FundSharesReported value% of valueQuarter
BlackRock, Inc. trimmed14,584,944$2.7B9.1%2026-Q1
STATE STREET CORP added11,372,750$2.1B7.1%2026-Q1
VANGUARD CAPITAL MANAGEMENT LLC new10,735,547$2.0B6.7%2026-Q1
WELLINGTON MANAGEMENT GROUP LLP trimmed9,651,472$1.8B6.0%2026-Q1
VANGUARD PORTFOLIO MANAGEMENT LLC new9,285,633$1.7B5.8%2026-Q1
Capital International Investors trimmed7,326,778$1.4B4.6%2026-Q1
Aristotle Capital Management, LLC trimmed4,866,481$899M3.1%2026-Q1
GEODE CAPITAL MANAGEMENT, LLC added4,336,996$798M2.7%2026-Q1
BANK OF AMERICA CORP /DE/ added4,199,433$776M2.6%2026-Q1
Capital Research Global Investors new4,010,550$741M2.5%2026-Q1
Invesco Ltd. trimmed2,977,272$550M1.9%2026-Q1
PRICE T ROWE ASSOCIATES INC /MD/ trimmed2,715,107$502M1.7%2026-Q1
DEUTSCHE BANK AG\ trimmed2,547,037$470M1.6%2026-Q1
GOLDMAN SACHS GROUP INC added1,935,162$357M1.2%2026-Q1
MASSACHUSETTS FINANCIAL SERVICES CO /MA/ trimmed1,772,601$331M1.1%2026-Q1
Legal & General Group Plc added1,616,380$299M1.0%2026-Q1
NORTHERN TRUST CORP added1,549,694$286M1.0%2026-Q1
DZ BANK AG Deutsche Zentral Genossenschafts Bank, Frankfurt am Main added1,490,653$275M0.9%2026-Q1
WELLS FARGO & COMPANY/MN trimmed1,329,328$246M0.8%2026-Q1
Amundi added1,302,886$241M0.8%2026-Q1
Perpetual Ltd trimmed1,240,469$229M0.8%2026-Q1
RAYMOND JAMES FINANCIAL INC added1,206,752$223M0.8%2026-Q1
NORGES BANK trimmed1,432,906$221M0.8%2026-Q1
Pictet Asset Management Holding SA added1,175,415$217M0.7%2026-Q1
UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC added1,063,678$196M0.7%2026-Q1
SFMG, LLC trimmed1,058,545$196M0.7%2026-Q1
CHARLES SCHWAB INVESTMENT MANAGEMENT INC added1,036,621$191M0.6%2026-Q1
ProShare Advisors LLC added1,023,862$189M0.6%2026-Q1
AMERICAN CENTURY COMPANIES INC trimmed1,002,458$185M0.6%2026-Q1
Nuveen, LLC added947,508$175M0.6%2026-Q1
VANGUARD FIDUCIARY TRUST CO new930,642$172M0.6%2026-Q1
Bank of New York Mellon Corp trimmed892,696$165M0.6%2026-Q1
GQG Partners LLC added887,204$164M0.6%2026-Q1
PNC FINANCIAL SERVICES GROUP, INC. added886,291$164M0.6%2026-Q1
BNP PARIBAS FINANCIAL MARKETS added834,718$154M0.5%2026-Q1
AQR CAPITAL MANAGEMENT LLC added820,885$151M0.5%2026-Q1
COHEN & STEERS, INC. added800,246$148M0.5%2026-Q1
HSBC HOLDINGS PLC trimmed780,184$144M0.5%2026-Q1
CBRE INVESTMENT MANAGEMENT LISTED REAL ASSETS LLC added757,953$140M0.5%2026-Q1
DIMENSIONAL FUND ADVISORS LP added752,986$139M0.5%2026-Q1
CITADEL ADVISORS LLC added751,604$139M0.5%2026-Q1
UBS Group AG added718,687$133M0.5%2026-Q1
SILVERCREST ASSET MANAGEMENT GROUP LLC trimmed707,225$131M0.4%2026-Q1
ENVESTNET ASSET MANAGEMENT INC added674,566$125M0.4%2026-Q1
PFA Pension, Forsikringsaktieselskab added668,040$123M0.4%2026-Q1
DUFF & PHELPS INVESTMENT MANAGEMENT CO trimmed607,945$112M0.4%2026-Q1
NEUBERGER BERMAN GROUP LLC added601,090$111M0.4%2026-Q1
Chevy Chase Trust Holdings, LLC added518,713$96M0.3%2026-Q1
SEI INVESTMENTS CO trimmed512,825$95M0.3%2026-Q1
PRINCIPAL FINANCIAL GROUP INC added507,404$94M0.3%2026-Q1
ROYAL BANK OF CANADA trimmed503,937$93M0.3%2026-Q1
Nilsine Partners, LLC trimmed491,331$91M0.3%2026-Q1
Swiss National Bank added474,700$88M0.3%2026-Q1
CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM trimmed473,753$88M0.3%2026-Q1
HUNTINGTON NATIONAL BANK added467,982$86M0.3%2026-Q1
Clark Capital Management Group, Inc. added432,477$80M0.3%2026-Q1
EARNEST PARTNERS LLC trimmed422,810$78M0.3%2026-Q1
Mitsubishi UFJ Asset Management Co., Ltd. added397,172$73M0.2%2026-Q1
Sumitomo Mitsui Trust Group, Inc. trimmed394,689$73M0.2%2026-Q1
AVIVA PLC added383,702$71M0.2%2026-Q1
BARCLAYS PLC added373,342$69M0.2%2026-Q1
Energy Income Partners, LLC added363,311$67M0.2%2026-Q1
Vanguard Global Advisers, LLC new360,844$67M0.2%2026-Q1
T. Rowe Price Investment Management, Inc. added358,652$66M0.2%2026-Q1
RHUMBLINE ADVISERS trimmed353,960$65M0.2%2026-Q1
JENNISON ASSOCIATES LLC trimmed346,090$64M0.2%2026-Q1
FIRST TRUST ADVISORS LP trimmed340,408$63M0.2%2026-Q1
BENJAMIN EDWARDS INC trimmed339,303$63M0.2%2026-Q1
BAHL & GAYNOR INC added335,750$62M0.2%2026-Q1
Capital International, Inc./CA/ added325,613$60M0.2%2026-Q1
Boston Trust Walden Corp trimmed324,927$60M0.2%2026-Q1
MANUFACTURERS LIFE INSURANCE COMPANY, THE trimmed323,423$60M0.2%2026-Q1
KBC Group NV trimmed316,327$58M0.2%2026-Q1
TORONTO DOMINION BANK trimmed309,461$57M0.2%2026-Q1
Vest Financial, LLC added307,562$57M0.2%2026-Q1
VANGUARD ASSET MANAGEMENT, Ltd new303,715$56M0.2%2026-Q1
COMMONWEALTH OF PENNSYLVANIA PUBLIC SCHOOL EMPLS RETRMT SYS trimmed301,973$56M0.2%2026-Q1
NEW YORK STATE COMMON RETIREMENT FUND trimmed295,457$55M0.2%2026-Q1
California Public Employees Retirement System trimmed290,843$54M0.2%2026-Q1
NOMURA ASSET MANAGEMENT CO LTD added289,580$53M0.2%2026-Q1
MILLENNIUM MANAGEMENT LLC added261,421$48M0.2%2026-Q1
SCHRODER INVESTMENT MANAGEMENT GROUP added259,231$48M0.2%2026-Q1
ROYAL LONDON ASSET MANAGEMENT LTD added255,035$47M0.2%2026-Q1
Munich Reinsurance Co Stock Corp in Munich trimmed251,761$47M0.2%2026-Q1
Aventail Capital Group, LP added247,838$46M0.2%2026-Q1
National Pension Service added244,687$45M0.2%2026-Q1
CITIGROUP INC trimmed241,707$45M0.2%2026-Q1
Partners Group Holding AG trimmed238,206$44M0.1%2026-Q1
STIFEL FINANCIAL CORP added232,998$43M0.1%2026-Q1
Aberdeen Group plc added228,217$42M0.1%2026-Q1
Clearbridge Investments, LLC added221,869$41M0.1%2026-Q1
M&G PLC trimmed201,418$37M0.1%2026-Q1
EXCHANGE TRADED CONCEPTS, LLC added195,457$36M0.1%2026-Q1
LPL Financial LLC added194,277$36M0.1%2026-Q1
Allspring Global Investments Holdings, LLC added189,256$35M0.1%2026-Q1
Eurizon Capital SGR S.p.A. trimmed189,350$35M0.1%2026-Q1
CANADA LIFE ASSURANCE Co trimmed188,054$35M0.1%2026-Q1
VANGUARD GROUP INC added21,032,449$3.5B12.0%2025-Q4 stale
MEAG MUNICH ERGO, Kapitalanlagegesellschaft mbH trimmed275,000$42M0.1%2025-Q2 stale
MIZUHO MARKETS AMERICAS LLC trimmed240,814$40M0.1%2025-Q4 stale

Ownership over time

Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.

HoldersTotal shares

Reading this table

Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.

About 13F filings

A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.

Learn how to read institutional ownership