Gerald Tsai Jr. (Chinese: 蔡至勇; pinyin: Cài Zhìyǒng; March 10, 1929 – July 9, 2008) was a billionaire investor and philanthropist who helped build Fidelity Investments into a mutual fund powerhouse. Tsai was a controversial figure. He pioneered the use of momentum investing in money management during the 1950s and 1960s. After starting Fidelity Investments' first publicly sold aggressive growth fund in 1958, the Fidelity Capital Fund, he later founded the Manhattan Fund, an aggressive growth fund, in 1965. Tsai sold his interest in the fund complex in 1968 but continued to manage the funds. By 1969 the funds collapsed, losing 90% of their value. An early proponent of momentum investing, Tsai's specialty was concentrating his portfolios on narrow batches of glamour stocks, including Xerox a