New research identifies 10,443 critically endangered species worldwide, with effective protection strategies available if funding and political will follow. More than 1,500 species, or 15% of the critically endangered species, are estimated to have fewer than 50 mature individuals remaining in the wild. Just 16 countries hold more than half of all critically endangered species, with concentrations across the Caribbean islands, Atlantic coastal regions of South America, the Mediterranean, Cameroon, Lake Victoria, Madagascar and Southeast Asia. Improving the status of critically endangered species would cost between an estimated $1 billion and $2 billion annually, a small fraction of global economic activity and less than 2% of the net worth of billionaires Elon Musk, Jeff Bezos or Mark Zuckerberg.