ARM Holdings plc (LSE: ARM, NASDAQ: ARMH) is a British multinational semiconductor and software design company headquartered in Cambridge. Its largest business is in processors, although it also designs software development tools under the RealView and Keil brands, systems and platforms, system-on-a-chip infrastructure and software. It is considered to be market dominant in the field of mobile phone chips and is arguably the best-known of the 'Silicon Fen' companies.

The company was founded as Advanced RISC Machines, ARM, a joint venture between Acorn Computers, Apple Computer (now Apple Inc.) and VLSI Technology. The new company intended to further the development of the Acorn RISC Machine's RISC chip, which was originally used in the Acorn Archimedes and had been selected by Apple for their Newton project. The design was flexible and is now the processing core for many custom application-specific integrated circuits.

ARM Holdings has a primary listing on the London Stock Exchange and is a constituent of the FTSE 100 Index. It has a secondary listing on NASDAQ.