[2][3] Important cities and towns linked by the M4 include (from east to west) London, Slough, Bracknell, Maidenhead, Reading, Newbury, Swindon, Bath, Bristol, Newport, Cardiff, Port Talbot and Swansea.
[4] Technology companies with major operations in the area include Adobe, Amazon, Citrix Systems, Dell, Huawei, Lexmark, LG, Microsoft, Novell, Nvidia, O2, Oracle, Panasonic, SAP, and Symantec.
Reading is home to many information technology and financial services businesses, including Cisco, Microsoft,[6] ING Direct,[7] Oracle,[8] Prudential,[9] Yell Group[10] and Ericsson.
[17] The major Welsh towns and cities along the M4 corridor are Bridgend, Cardiff, Llanelli, Neath, Newport, Port Talbot and Swansea.
[25] The opening of the Second Severn Crossing in 1996 resulted in the previous M4 and bridge, serving Chepstow, being renumbered the M48, although the area is still generally considered as falling within the M4 corridor.