Instinet intends to terminate 300 of its employees -- or roughly 17 percent of its collective, full-time workforce -- during this quarter. The layoffs are part of Instinet's plan to reduce its operating costs by $100 million by the end of 2003. Instinet is trying to eliminate redundant positions it inherited when it acquired Island, its one-time ECN Rival, on Sept. 20. The announcement of the cost reduction plan comes in the wake of the exit of Matt Andresen, the former Island chief executive officer. Andresen, who was scheduled to take a chief operating officer post with Instinet, recently accepted a position as head of global trading at the securities firm Sanford C. Bernstein.