"US Treasuries are among the safest and most liquid investments in the world, and we take very seriously our commitment to keep them that way." - Janet Yellen, speaking at her confirmation hearing as Treasury Secretary in January 2021."US Treasuries are among the safest and most liquid investments in the world, and we take very seriously our commitment to keep them that way." - Janet Yellen, speaking at her confirmation hearing as Treasury Secretary in January 2021.