13F filing

A 13F filing is a quarterly report that large investment managers must submit to the SEC (Securities and Exchange Commission, the government agency that oversees stock markets) showing which stocks they own. Think of it as a public snapshot of a professional investor's portfolio. You'll encounter these filings when researching what famous investors or big funds are buying and selling—it's a way to peek at their stock picks with a 45-day delay. For example, if you see that a well-known fund manager just filed a 13F showing they bought 100,000 shares of TechCorp, that might influence your own research. The catch: by the time you read it, they may have already made different moves, so it's historical data, not a crystal ball.