US stock market retail investors could soon have access to complex structured debt investments previously accessible only to hedge funds and institutional investors.

Investment vehicles linked to fund managers such as Bear Stearns Asset Management and Highland Capital have sought regulatory permission to list on US stock markets. They own credit assets including “equity” tranches of collateralised debt obligations – investments that carry high returns but which can be wiped out by the first few defaults in the portfolios of underlying debt that back them.