Whale watching (13F tracking)

Whale watching is tracking what large institutional investors (called "whales" because of their size) are buying and selling by reading their SEC filings, particularly Form 13F. A 13F is a quarterly report that big money managers must file showing their stock holdings. Since these investors have teams of analysts and deep pockets, retail investors often assume their picks are worth copying. You'll encounter this on financial forums and research sites where people discuss newly filed 13Fs. For example, if a famous hedge fund manager just bought a big stake in a company, retail investors might notice and get interested too. It's basically financial detective work—legal and public, but requiring some digging.