Dorsey's fortune is derived from his holdings in Block and X Corp, formerly known as Square and Twitter respectively.

Dorsey owns about 9% of Block, according to its June 2024 filing. In April 2020, he pledged $1 billion of his stake in the company to coronavirus relief efforts, having previously committed to giving away about half of his stake to Start Small Foundation, his charity, according to the company's 2015 prospectus. About $700 million in stock was donated in August 2020, according to a company filing. The remaining shares are included in his net worth until they are gifted.

Dorsey owns 2.9% of San Francisco-based Twitter, according to the company's 2022 proxy. The company was taken private by Elon Musk in October 2022 at $54.20 a share. Dorsey is assumed to have kept his stake in the firm based on his public statements. The value of Twitter, which has since been renamed X Corp, is adjusted based on the price disclosed by investor Fidelity Blue Chip Growth Fund in a filing.

In August 2011, Dorsey and two other Twitter shareholders sold 22.6 million shares to three investment banks for $15.93 a share, according to the prospectus. Dorsey is credited with one third of this amount.

The value of his cash holdings is based on an analysis of share sales, dividends, market performance, taxes and charitable contributions.