US billionaire philanthropist MacKenzie Scott announced on Tuesday that she has donated $2.7 billion to 286 non-profit organizations.

Scott, former wife of Amazon founder Jeff Bezos, said in a statement that she and her husband, Dan Jewett, made the donations as a "sign of trust and encouragement" to the recipients, showing concern about the growing concentration of wealth in a small proportion of individuals.

Scott and Jewett worked with a team of researchers and philanthropy consultants "to donate a fortune that was made possible by systems that needed changing," he noted.

"In this effort," she said, "we are governed by a humble belief that it would be better if disproportionate wealth were not concentrated in a small number of hands, and that solutions would be better designed and implemented by other people."

In 2020, Scott made two similar surprise announcements, giving $6 billion for support in the context of the covid-19 pandemic, gender equality, African-American colleges and universities.

The 286 new recipients include "heritage-focused" non-profit organizations working in long-neglected areas, and were selected from a rigorous research and analysis process, Scott said.