Jack Dorsey, the CEO of both Twitter and digital payments platform Square, said on Tuesday, April 7 that he will donate $1 billion worth of equity in Square to his Start Small LLC to fund COVID-19 relief around the world.

Dorsey made the announcement in a tweet, revealing that the sum equates to roughly 28% of his current net worth, or about $3.6 billion, The Verge says.

The announcement marks the most significant philanthropic effort from the 43-year-old tech executive in his career.

Dorsey says the $1 billion going into Start Small will be publicly tracked, and he even tweeted the public Google Sheets spreadsheet that will track the spending. It includes an existing $100,000 donation Dorsey gave to America's Food Fund.

He says following the COVID-19 relief effort, Start Small will shift focus to “girls' health and education, and UBI,” or universal basic income.