Dell acquired 7.37 million of the company's shares for $13.57 each on Friday, according to filing with the U.S. Securities and Exchange Commission on Monday.
The CEO now directly or indirectly owns roughly 263 million Dell shares, a stake valued at around $3.5 billion. Michael Dell is the company's largest shareholder, according to Thomson Reuters I/B/E/S.
Dell shares are down around 7 percent this year.
In an interview earlier this month, Michael Dell argued that some on Wall Street are not giving the company enough credit for the success of its transformation efforts, as technology vendor attempts to diversify its business and boost margins.
Shares of Round Rock, Texas-based Dell closed down 2.1 percent at $13.36 on the Nasdaq.
(Reporting by Gabriel Madway, editing by Matthew Lewis)