Perhaps the biggest influence on most big superannuation funds is the sharemarket.
The typical managed fund has about half its assets in shares, so market movements can make a big difference to what is left for members when they hit retirement.
It's worthwhile, therefore, to think about what's driving the sharemarket, and whether it's sustainable.
In the first 10 months of this financial year, rising share prices meant the typical super fund had returned a whopping 15 per cent, even if things cooled off in May.
But you can't help but notice that these gains came against a weakening economic backdrop, with many companies complaining that things remain tough.
It begs the question: if growth is weak, why did share prices start 2013 so strongly? And, more importantly, can it last?
Most experts agree that shares have risen this year because of the extraordinary measures being taken around the world to reignite growth.
As central banks slash interest rates and pump money into the system, it has lowered the return on government bonds and forced investors such as pension funds to snap up other assets that can provide a good return.
In the jargon, there has been a mad rush for "yield", with investors piling into high-dividend stocks such as Telstra and the banks.
You can see this trend in the graph, which comes from Macquarie strategist Tanya Branwhite. It includes a "high-yield" index of Aussie stocks, such as banks, telecommunication, listed property trusts and utilities. As the graph shows, these high-yields stocks have been a smash-hit with investors, rising 50 per cent since mid 2011, far ahead of the rest of the market. In short, the high-yield stocks have been driving market performance.
But the growing question on many investors' minds is whether a rally built on a search for yield is sustainable.
In recent weeks, a growing number of experts have been raising doubts. Branwhite says the yield-induced rally is now "maturing" and it may be time to look at "growth" stocks, such as BHP.
Greg Perry, a former Colonial First State fund manager who was regarded as the best stock-picker in the 1990s, also describes the search for yield as "very mature".
What do they mean by mature? Basically, they are concerned that stocks have become too expensive. If investors are simply pushing up share prices because they are looking for yield, there are risks of bubbles forming.
The Commonwealth Bank, for instance, has been trading at a price of about 15 times current earnings, which analysts say is close to its highest ever level. With little in the way of credit growth, sceptics believe the bank is overpriced.
Even the $87 billion Future Fund, one of the biggest investors in the country, last week warned against chasing yield purely for its own sake.