With the gift, the group's endowment is more than $7.5 million, according to a spokesperson.
In addition to presenting an annual series at Carnegie Hall and chamber concerts around New York City, OSL partners with various arts organizations, appearing at Caramoor, at galas and recitals, and on recordings.
In a recent article in Business Week magazine, OSL president Marianne Lockwood contrasted the flexible, part-time group to major orchestras, "made up of tenured musicians who play as an orchestra in a permanent venue."
"The [OSL] expands and contracts as needs dictate," she wrote, "and our musicians are equally at home in Carnegie Hall or New York City's public schools. This flexibility—borne of necessity—has become a great asset, enabling us to sustain a financially viable model with no deficit."