In that publication, we noted that limited evidence suggests that income trusts can enhance market completeness in a couple of ways. First, income trusts can provide diversification benefits to investors, because trusts can have different risk-return characteristics than either equities or bonds. Second, the income trust structure appears to allow some firms improved access to market financing.
So, insofar as income trusts allow investors to achieve risk-return benefits that they could not otherwise achieve, and serve as a source of financing to firms that might not otherwise have had access to markets, it can be said that income trusts enhance market completeness, and therefore support financial system efficiency.