Restricted securities, typically bought in a private placement, require a holding period of six months for reporting issuers or a year otherwise. Affiliates face extra conditions whenever they sell, including a volume cap of the greater of 1% of shares outstanding or average weekly volume over four weeks, brokered transactions, and a form-144 notice above modest thresholds.
Non-affiliates who have held long enough can usually sell freely once information conditions are satisfied, which is why lockup expiries and the one-year mark matter for supply in recently listed names.
Legends on certificates are removed only with a transfer agent opinion, which is why restricted holders often cannot sell quickly even when they are technically eligible.
Related: securities-act-1933, form-144, private-placement-regulation-d, section-16-insider, float