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Allegheny Technologies Inc., a steel company that trades on the New York Stock Exchange under the symbol 'ATI'.

ATI Technologies Inc., a manufacturer of graphics cards.

The ATI in ATI Technologies goes even further to mean Array Technologies Incorporated.

Auckland Technical Institute, now Auckland University of Technology

Advanced Training Institute, a home education program developed by Institute in Basic Life Principles.

Automation Technology Inc., a provider of web-based collaborative outage work-scope planning software for the electrical power generation industry.

Allied Telesis Inc., a manufacturer of computer network products, formerly known as Allied Telesyn.

A. Tarricone, Inc., a fuel company operating a chain of gas stations in parts of New York State.

ATI (group), a musical group.

Agricultural Technical Institute, a campus located in Wooster, Ohio part of The Ohio State University system.

A. T. I., a 1944 collection of poems by A. P. Herbert

Tunisian Internet Agency (Agence tunisienne d'Internet), a Tunisian ISP.