It's a different mechanism, because the CPP is a defined benefit plan. The returns of the CPP funds are affected by market returns. However, the benefit that flows to workers is a defined benefit. So it's a guaranteed benefit. What would happen in the extreme, if you had many, many years of negative returns and the value of the funds started to climb, is that you would likely have to raise contribution rates. So current workers and employers would be paying more to pay out the guaranteed benefits of retirees.
On February 16th, 2012. See this statement in context.