Institutional investor is a term for entities which pool money to purchase securities and other investment assets. Institutional investors include money managers, banks, insurance companies, commercial trusts, pensions, hedge funds, REITs, investment advisors, endowments, and mutual funds. Institutional investors account for half of the volume of trades on the New York Stock Exchange. They move large blocks of shares and influence the direction of the entire stock market.
Institutional Investor (Wikipedia)