It has been estimated that over 200 companies were hard disk drive manufacturers at one time or another. Besides competing on features such as hard disk (HDD) data density and latencies, many of those companies started to support new, smaller form factors that enabled the ever-reducing physical sizes of computing devices. Most of that industry has been reduced to five strong vendors through bankruptcy and acquisition. As of 2011, these vendors are (alphabetically): HGST, Samsung, Seagate, Toshiba, and Western Digital. The first two of these may be acquired later in 2011, which would result in only three manufacturers of hard drives.
The following is a list of notable defunct HDD manufacturers: