An institutional investor is an entity which pools money to purchase securities, real property, and other investment assets or originate loans. Institutional investors include commercial banks, central banks, credit unions, government-linked companies, insurers, pension funds, sovereign wealth funds, charities, hedge funds, REITs, 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. In 2019, the world's top 500 asset managers collectively managed $104.4 trillion in Assets under Management (AuM). Although institutional investors appear to be more sophisticated than retail investors, it remains unclear if professional active investment managers can reliably enhance risk-adjusted returns by an amount that exceeds fees and expenses of investment management, due to issues with limiting agency costs. 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 US asset managers together owned an average of 18% in the S&P 500 Index and together constituted the largest shareholder in 88% of the S&P 500 by 2015. The potential of institutional investors in infrastructure markets is increasingly noted after financial crises in the early twenty-first century. History Ancient Rome and Islam Roman law ignored the concept of juristic person, yet at the time the practice of private evergetism (which dates to, at least, the 4th century BC in Greece) sometimes led to the creation of revenues-producing capital which may be interpreted as an early form of charitable institution. In some African colonies in particular, part of the city's entertainment was financed by the revenue generated by shops and baking-ovens originally offered by a wealthy benefactor. In the South of Gaul, aqueducts were sometimes financed in a similar fashion. The legal principle of juristic person might have appeared with the rise of monasteries in the early centuries of Christianity. The concept then might have been adopted by the emerging Islamic law. The waqf (charitable institution) became a cornerstone of the financing of education, waterworks, welfare and even the construction of monuments. Alongside some Christian monasteries the waqfs created in the 10th century AD are amongst the longest standing charities in the world (see for instance the Imam Reza shrine). Pre-industrial Europe Following the spread of monasteries, almshouses and other hospitals, donating sometimes large