Fidelity Investments is one of the leading brokerage and investment companies in the world. And their mutual funds are some of the most subscribed in the industry.
Most of the stocks you will find in FZROX are common stocks using an adjustable floated market-weighted index which reflects the performance of the equity market.
The managers of FXAIX rely on statistical sampling. They evaluate each stock based on current trends, company profiles, and, most importantly, historical data to make their choice.