Twitter CEO Jack Dorsey is setting aside $1 billion in stock to establish a philanthropic venture focused initially on global relief efforts for the COVID-19 pandemic. Dorsey, who is also CEO of the financial-payments startup Square, will bequeath the new venture shares from his Square holdings.

Dorsey announced the new venture, called Start Small, in a series of tweets, and said the contribution amounts to 28% of his fortune. The organization will disclose all transfers, sales and grants on a public Google Doc spreadsheet.

Start Small won’t be limited to COVID-19 work. “Once we have disarmed this pandemic,” he wrote, the organization will shift its focus to girls’ health and research into universal basic income, the idea that governments should guarantee a minimum income for all citizens.