Complex sentence: Ray Dalio founded the company in 1975 and was joined by Bob Prince, who in 1986 became the "director of research and trading" and later, a co cheif investment officer (CIO) with an ownership stake in the company.
Split into simpler sentences: Ray Dalio founded the company in 1975 and was joined by Bob Prince, who in 1986 became the "director of research and trading". Later on Prince became a co cheif investment officer (CIO) with an ownership stake in the company.