When did ATO join the S&P 500?

Atmos Energy joined the S&P 500 index on 2019-02-15.

What sector is ATO in?

ATO is in the Utilities sector, Gas Utilities industry.

ATO — Atmos Energy

Name: ATO Institutional Holdings (13F) — 2026Q1
Creator: SEC EDGAR
License: https://www.sec.gov/data

Gas Utilities · Utilities

ATMOS Energy Corporation provides natural gas services. The company operates through three segments: distribution, pipeline, and storage. The distribution segment handles regulated natural gas distribution and related sales. The pipeline and storage segment includes the operations of Atmos Pipeline-Texas Division and natural gas transmission services.

Key Facts

Status	Active
Sector	Utilities
Industry	Gas Utilities
Joined	2019-02-15
Tenure	7 yrs

S&P 500 Timeline

2019-02-15Joined S&P 500

Industry Peers

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Sector Peers

AEE AEP AES AWK CEG CMS CNP D DTE DUK

Institutional Holdings (13F)

1,015 institutions hold ATO, totaling 200.0M shares ($34.5B) · As of 2026Q1

Rank	Institution	Shares	Value
1	VANGUARD CAPITAL MANAGEMENT LLC	21.5M	$4.0B
2	BlackRock, Inc.	17.5M	$3.2B
3	STATE STREET CORP	11.4M	$2.1B
4	DZ BANK AG Deutsche Zentral Genossenschafts Bank, Frankfurt am Main	14.9M	$1.8B
5	WELLINGTON MANAGEMENT GROUP LLP	9.7M	$1.8B
6	VANGUARD PORTFOLIO MANAGEMENT LLC	9.3M	$1.7B
7	MORGAN STANLEY	8.7M	$1.5B
8	Capital International Investors	7.3M	$1.4B
9	Aristotle Capital Management, LLC	4.9M	$899M
10	GEODE CAPITAL MANAGEMENT, LLC	4.3M	$798M

View all holders →

Data source: Wikipedia · CC BY-SA 4.0 · SEC EDGAR 13F · Updated 2026-07-10