Joonhee Won founded TStone in 2001 as an investment firm focused on principal investments. Prior to founding TStone, he was a Managing Director and the head of investment banking at Salomon Smith Barney Korea, where he completed over 20 M&A and capital markets transactions. Earlier in his career, Joonhee Won worked as an investment banker at Credit Suisse First Boston (Hong Kong), Lehman Brothers (New York), and Jardine Fleming (Seoul).

Joonhee Won holds an M.B.A. from Harvard Business School and a B.A., with distinction, in government and economics from Cornell University.