In general, portfolio insurance can be thought of as holding two portfolios, the first portfolio can be viewed as the safe or riskless portfolio with value equal to the level of protection desired. This level is called the floor and is the lowest value the portfolio can have. For certain strategies this can be held constant or allowed to change over time as market conditions or needs change. The second portfolio consists of the difference between the total value of the portfolio and the floor, commonly called the portfolio cushion. These assets consist of a leveraged position in risky assets. To insure the portfolio, the cushion should be managed as never to fall below zero in value because of the limited-liability property of common stock.