This growth-oriented fund primarily invests in large and mid-sized companies, operating with a long-term outlook, exceptionally low portfolio turnover, and a time-tested investment approach. Established in 1984, PRIMECAP Management Company, the fund's advisor, employs a unique strategy where several portfolio managers independently oversee distinct segments of the portfolio. This multi-manager structure is designed to promote a variety of investment viewpoints. A key risk factor is the fund's potential for significant concentration in a handful of sectors, most notably technology and health care. This sectoral focus can lead to considerable short-term performance fluctuations, particularly when these industries experience strong rallies or downturns. Investors seeking to enhance an already diversified portfolio, and who possess a long-term investment horizon, may find this fund suitable as a supplementary holding.