They can borrow money using the portfolio as collateral, interest free or pegged to inflation, to be repaid either when the stock is released or over time. Alth

They can borrow money using the portfolio as collateral, interest free or pegged to inflation, to be repaid either when the stock is released or over time. Although, it'd be a bit more complex than standard collateral since there'd have to be a "margin call" mechanism, where assets in the portfolio have to be sold to cover the debt if they drop too far.