Twitter founder and chief executive Jack Dorsey is setting aside one billion dollars (£812 million) in stock to establish a philanthropic venture aimed initially at fighting the Covid-19 pandemic.

Mr Dorsey, who is also chief executive of the financial-payments startup Square, will bequeath the new venture shares from his Square holdings.

The 43-year-old announced the new venture, called Start Small, in a series of tweets, and said the contribution amounts to 28% of his fortune.

The organisation will disclose all transfers, sales and grants on a public Google Doc spreadsheet.

Start Small will not be limited to fighting the pandemic, Mr Dorsey said.

“Once we have disarmed this pandemic,” he wrote, the organisation 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.