Bill Gates owns a very significant amount of Microsoft stock.
Since when is $11.3 billion held by one person in one company, not a lot? It's one of the largest single positions held by any person on the planet in a given company. That position is so large, by itself it would nearly qualify a person into the top 100 richest list globally.
Top Microsoft mutual fund position: Vanguard Total Stock Market Index Fund, 155 million shares.
Bill Gates: 167 million shares.
He'd be the seventh largest institutional holder in Microsoft - a $528 billion company.