Stephanie Cuskley, a nonprofit and financial-services veteran, will be the new chief executive of the Leona M. and Harry B. Helmsley Charitable Trust, replacing John Ettinger. Previously, Ms. Cuskley, 55, served as chief executive of NPower, a national group that provides technology assistance to charities, schools, and individuals. Before that, Ms. Cuskley worked for investment banks, including Drexel Burnham Lambert and JPMorgan Chase. The Helmsley Trust, which posted $5.4 billion in assets last year, supports a number of health programs, including efforts to improve rural health care and treat Type I diabetes. It also supports programs in New York and Israel and efforts to improve education and assist vulnerable children. The trust’s predecessor organization, the Harry B. Helmsley Foundation, was created by Mr. Helmsley in the 1950s. He died in 1997. Two years after his widow’s death in 2007, and following a court battle over her estate, the philanthropy sold off several large assets from her estate, formalized its grant-making priorities, and began making large gifts.