I'm honestly not sure if it's 50% or not, but I suppose the idea is that not everyone withdraws at the same time. Ideally, you would only sell off assets that

I'm honestly not sure if it's 50% or not, but I suppose the idea is that not everyone withdraws at the same time. Ideally, you would only sell off assets that you need to raise capital to pay for benefits. Also, there's new money coming into the fund by employees paying in, and I'm not sure they can stop. But in general, if everyone wanted to sell their assets at the same time, that's when the stock market "crashes", because there's no buyers. I suppose the pension fund managers can make these types of decisions, but in general they are governed by rules and best practices in terms of what investments they can make. If these funds stopped investing their money, they'd be at greater risk of inflation, and where would they put it? What would be the next step? But you're right there is a lot of retirement money in the market, and when people start to retire, some of that money will go out of the market, but also a lot of people are trying to live only off the interest/dividends, and keep the principal because they are worried they will live longer than they were expecting.