20-F and 40-F
Similar to 10K
For foreign private issuers
40 = Canada
20 = other non US registrants
11-K
Annual report if employee benefit plans
Form 6-K
Similar to 10Q
Semi-annually by foreign private issuers
Forms 3, 4, and 5
For directors, officers, or beneficial owners of more than 10% of a class of equity stock