MacKenzie Scott, the billionaire philanthropist known for her impromptu multi-billion dollar donations to charities and racial equity causes, announced Tuesday that she has given $2.7 billion to 286 organizations. It is the third round of no-strings-attached, major philanthropic gifts Scott has made, which together rival the charitable contributions made by the largest foundations.

Scott, the ex-wife of Amazon founder Jeff Bezos, wrote in a Medium post that she and her husband, Dan Jewett, made the donations to enable the recipients to continue their work and as a “signal of trust and encouragement” to them and others.

And she made clear in her announcement that she is troubled by the increasing concentration of vast wealth among a small proportion of individuals. She and Jewett worked with a team of researchers and philanthropy advisors “to give away a fortune that was enabled by systems in need of change.”

“In this effort,” she said, “we are governed by a humbling belief that it would be better if disproportionate wealth were not concentrated in a small number of hands and that the solutions are best designed and implemented by others.”

In 2020, Scott made two similar surprise announcements in which she donated a combined $6 billion to COVID-19 relief, gender equity, historically Black colleges and universities and other schools. Similar to the organizations she picked as recipients last year, Scott said the 286 organizations chosen for Tuesday’s announcement were selected from a rigorous process of research and analysis. That effort included “equity-oriented” nonprofits working in long-neglected areas.

“Because we believe that teams with experience on the front lines of challenges will know best how to put the money to good use, we encouraged them to spend it however they choose,” she wrote.

Scott’s wealth, estimated by Forbes at roughly $60 billion, has only grown since she divorced from Bezos in 2019 and walked away with a 4% stake in Amazon. Shortly after the split, the 51-year-old signed the Giving Pledge, a commitment developed by Bill and Melinda Gates, and Warren Buffett to get the world’s richest to give a majority of their wealth during their lifetimes or in their wills. Jewett also became a signatory earlier this year.

Their latest recipients range from universities — including $40 million apiece to the University of Central Florida and the University of Texas at San Antonio — to refugee resettlement groups and arts and culture organizations that have suffered from a drop in giving as donors focused on more urgent needs brought on by the coronavirus pandemic.

The donations also went to nonprofits that focus on minority communities. The group Native Americans in Philanthropy, a recipient that connects philanthropic organizations to Native American-led nonprofits, said in a statement that the multi-million contribution will help them in their efforts to increase funding to tribal communities.

“MacKenzie Scott has recommitted to transformative work, the organizations that undertake it and the leaders whose ideas are often under-funded and overlooked,” Erik Stegman, the executive director of the group, said in a statement. “It’s important to note that she has also just written checks to these organizations, leaving her own interests to the side and giving up power to the organizations she’s funding.”

Scott’s concern about the enormous gap between the very wealthiest Americans and everyone else was underscored in a report last week from the nonprofit investigative journalism organization ProPublica. It reported that the richest 25 Americans pay less in tax than many ordinary workers do, once you include taxes for Social Security and Medicare.

Drawing upon Internal Revenue Service data on the country’s wealthiest people, ProPublica reported that some of them have paid no income tax, or nearly none, in some years. Among them is Scott’s former husband, Bezos, who, according to ProPublica, paid no income tax in 2007 and 2011.