Large Trader
What it is:
A large trader is a person or entity that trades more than 2 million shares or $20 million worth of shares in a single day, or 20 million shares or $200 million worth of shares in a single month.
How it works/Example:
Let's say Company XYZ is a pension fund that holds $1 billion of assets for a teachers union. The fund manager often makes large trades, and in some cases trades more than 2 million shares a day.
The Securities and Exchange Commission requires the fund manager to register as a large trader, meaning she must file a Form 13H ("Large Trader Registration"). The trader's trades receive an identification number from the SEC.
Why it matters:
Large traders have considerable influence over volumes and pricing in the market, which is why the SEC likes to keep an extra eye on them. Since 2011, the SEC has defined large traders, has required them to register via Form 13H (which they must update annually), and has required them to keep extra records regarding their trades.