Macintosh
Compaq, who had previously held the third place spot among PC manufacturers during the 1980s and early-mid 1990s, initiated a successful price war in 1994 that vaulted them to the biggest by the year end, overtaking a struggling IBM and relegating Apple to third place. Apple's market share further struggled due to the release of the Windows 95 operating system, which unified Microsoft's formerly separate MS-DOS and Windows products. Windows 95 significantly enhanced the multimedia capability and performance of IBM PC compatible computers, and brought the capabilities of Windows to parity with the Mac OS GUI.

Q: Who did Compaq overtake in the price war of 1994?
IBM