Bearer bonds with interest coupons attached, and bonds registered as to principal and interest, will be available in denominations of $500, $1,000, $5,000, $10,000, $100,000, and $1,000,000. Provisions will be made for the interchange of bonds of different denominations and of bearer and registered bonds, and for the transfer of registered bonds.
31 C.F.R. § 340.2