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 13F filings when researching what famous investors are buying and selling—it's a way to peek at their stock picks without waiting for them to announce anything. For example, if you noticed that a well-known fund manager just bought 100,000 shares of a company, that info came from a 13F filing. It's useful because these pros often have research teams and deep pockets, so their moves can hint at opportunities worth investigating yourself.