Regulation D (Reg D) is the SEC framework that exempts most private securities offerings from public-registration requirements under the Securities Act of 1933. Codified in Rules 504, 506(b), and 506(c), the regulation covers essentially all venture financing rounds in the US through Rule 506(b) and Rule 506(c), allowing companies to raise unlimited capital from accredited investors without registering the offering with the SEC. It is the regulatory backbone that makes private startup financing possible, and one of the few SEC frameworks every startup founder needs at least passing familiarity with.
The three rules in Regulation D: