Vanguard 500 Index Fund Institutional Select Shares 

This fund aims to mirror the performance of the S&P 500 Index, which serves as a widely recognized measure for the U.S. stock market and primarily consists of shares from major American corporations. To achieve this, the fund's advisor invests nearly all of its assets directly into the stocks that constitute the index, maintaining each holding in roughly the same proportion as its significance within that benchmark. It is important to note that this fund is categorized as non-diversified.