Gilbert Edmund Kaplan (March 3, 1941 – January 1, 2016) was an American businessman and financial publisher. He was also an aficionado of the music of Gustav Mahler, and an amateur conductor of Mahler's Symphony No. 2.
Kaplan was born in New York City on March 3, 1941. He studied at Duke University, and earned a bachelor's degree from The New School for Social Research. He later studied at New York University Law School. In 1963, Kaplan took a job as an economist with the American Stock Exchange, at a salary of $15,000 per year. Kaplan founded the magazine Institutional Investor in 1967. He was publisher of the magazine until 1990, and editor-in-chief for two more years, although he sold it in 1984. The New York Times reported: "The price was never disclosed but was rumored to be about $75 million."
Kaplan's interest in Mahler's Symphony No 2 dated back to 1965. In 1981, he began tutelage in conducting with Charles Zachary Bornstein. He rented Avery Fisher Hall in New York for his public conducting debut in 1982, leading the American Symphony and the Westminster Symphonic Choir. Originally, the orchestra had requested that no reviews be published, but Leighton Kerner of The Village Voice breached this requested embargo with a positive review of this performance. Subsequently, Kaplan conducted Mahler's Symphony No 2 in over 100 live performances over the remainder of his life. He established the Kaplan Foundation, dedicated to scholarship and the promotion of the music of Gustav Mahler. After personal research, he twice recorded Mahler's Second Symphony: with the London Symphony Orchestra in 1987, and with the Vienna Philharmonic in 2002. Mahler's Second Symphony was the only complete work he conducted in public, although he did separately record the Adagietto from Mahler's Symphony No. 5 in a studio recording.