Dell Inc founder Michael Dell bought $100 million of shares last week after the stock plunged following disappointing earnings.

Dell, the chairman and chief executive officer of the Round Rock, Texas-based company, paid $20.42 a share for 3.5 million shares on Sept 4, and $20.67 for 1.378 million on Sept 5, according to a filing on Monday with the Securities and Exchange Commission.

Profit last quarter missed analysts' estimates as the world's second-largest personal-computer maker said the US slump in technology spending was expanding abroad.