IBM ruled the computer industry for decades until it hired the tiny, unknown Microsoft to provide an operating system for its new range of personal computers in the early 1980s.

Bill Gates parlayed that breakthrough into industry dominance, proving his theory that software would be more valuable than hardware, so that by the end of 1999 Microsoft's market value was three times that of IBM's.

Throughout Microsoft's rise, IBM was pilloried as an old-fashioned, immobile Goliath that could not keep up with the computing revolution.

Since the Internet technology bubble burst in 2000, the tables have been reversed, and Microsoft's stock has been stagnant, as investors doubt its ability to move beyond its Windows operating system and Office suite of software, while younger rivals such as Google Inc. and Facebook steal the limelight.

Resurgent Apple Inc moved past Microsoft in terms of market value last year, and is now by far the world's biggest tech company.

According to Reuters data, Apple's market value stood at $308.3 billion Monday, IBM at $203.5 billion and Microsoft at $201.3 billion.

IBM shares were down 1.2 percent at $168.07 while Microsoft fell 1.6 percent at $24.10.