Regulation D is a regulation of the Securities and Exchange Commission of the United States, and is also a term for an investment strategy, mostly associated with hedge funds, based upon that regulation.

Regulation D, also known as "Reg D," exempts certain offerings of equity from many of the regulatory requirements that impose costs upon standard public offerings . A Reg D offering is intended to make access to the capital markets possible for small companies that could not otherwise bear those costs.

As a hedge-fund strategy, Reg. D refers to investment in micro- and small-capitalization public companies that are raising money in private capital markets. Often these securities are hedged by way of a look-back provision or a convertibility option with an exercise price that floats.