 An institutional investor is an entity which pulls money to purchase securities, real property, and other investment assets or originate loans. Institutional investors include banks, insurance companies, pensions, hedge funds, rights, investment advisors, endowments, and mutual funds. Operating companies which invest excess capital in these types of assets may also be included in the term. Activist institutional investors may also influence corporate governance by exercising voting rights in their investments. Although institutional investors appear to be more sophisticated than retail investors, it remains unclear if professional active investment managers can rely heavily in hands-risk adjusted returns by an amount that exceeds fees and expenses of investment management. Lending credence to doubts about active investors' ability to beat the market, passive index funds have gained traction with the rise of passive investors, the three biggest U.S. asset managers together owned an average of 18 percent in the S&Page 500 index and together constituted the largest shareholder in 88 percent of the S&Page 500 by 2015. The potential of institutional investors in infrastructure markets is increasingly noted after financial crises in the early 21st century.