There are economic agents that have more influence than others in financial markets. A person who invests 1,000 million euros will have more power of influence than a person who invests 1,000 euros. If a person sells 1,000 euros, they will have little effect on the market. On the other hand, if a person sells huge amounts of shares of a bank, the shares of this bank will probably go down. In theory, in the long term, no matter how high the amount, if the market is broad, that investor's operation will dissolve and make the financial market reflect an efficient price again.