ATI Technologies Inc., commonly called ATI, was a Canadian semiconductor technology corporation based in Markham, Ontario, that specialized in the development of graphics processing units and chipsets. Founded in 1985, the company listed publicly in 1993 and was acquired by AMD in 2006. As a major fabrication-less or fabless semiconductor company, ATI conducted research and development in-house and outsourced the manufacturing and assembly of its products. With the decline and eventual bankruptcy of 3dfx in 2000, ATI and its chief rival Nvidia emerged as the two dominant players in the graphics processors industry, eventually forcing other manufacturers into niche roles.

Markham is a city in York Region, Ontario, Canada. It is approximately 30 km (19 mi) northeast of Downtown Toronto. In the 2021 Census, Markham had a population of 338,503, which ranked it the largest in York Region, fourth largest in the Greater Toronto Area (GTA), and 16th largest in Canada.