Clay served as chairman of the East Hill Management LLC, an investment advisory firm he founded in 1997.
In addition from 1971 to 1997, Clay served on the board of Museum of Fine Arts.
Clay also served as a director for Plasso Technology Limited.
[4] Clay was also a supporter of astronomy, with one of his gifts through the Harvard College Observatory leading the Magellan Telescopes consortium to name one of the two 6.5-m components of the Magellan Telescope to be named for him, as well as a provider of Clay Postdoctoral Fellowships at the Smithsonian Astrophysical Observatory, part of the Center for Astrophysics | Harvard & Smithsonian.
[5] He also supported the Clay Center Observatory with its 24-inch telescope at the Dexter-Southfield School in Brookline, Massachusetts.