A common index fund system and method enables investment in entities that is indexed to a common index, rather than individual company performance. For small business entities, the creation, issuance, trading and management of fund shares as a liquid investment may be accomplished with, for example, a relatively stable industry-based risk. The entities receive value from a pool and in return make payments into the pool in an amount that varies according to the index, which causes a corresponding change in the value of the shares.