10-K
Annual Report
Full-year financial statements. Most important filing — read this first.
10-Q
Quarterly Report
Three-month financial update. Filed 3x per year between 10-Ks.
8-K
Current Report
Major events: earnings, M&A, CEO changes, bankruptcy. Time-sensitive.
13F
Institutional Holdings
What hedge funds and institutions own. Filed quarterly. Huge signal.
Form 4
Insider Transactions
When executives buy or sell their own company stock. Watch closely.
S-1
IPO Registration
Filed before going public. Contains all financial history and risk factors.