A method and system for underwriter offering of multi-class instruments including a central processing unit (CPU), a program memory, a structure database and an investor database. The structure database stores a structure representative of a plurality of classes of a multi-class instrument, and the system operates to (i) inform investors of class information related, respectively, to each class of the multi-class instrument, (ii) receive bid information from investors, (iii) modify the structure database in response to the bid information and subsequently inform investors with updated class information; and once it is determined that the underwriter can profitably underwrite the transaction, (iv) notify the underwriter of an amount of collateral to purchase to cover accepted bids.