They account for 42 per cent of the index by market capitalisation. The Magnificent 10 account for 50 per cent of the index and the Magnificent-''ish'' 50 account for 80 per cent of the ASX 200 index.

In other words, the Australian indices are a ''rock in a sock''.

A small group of large stocks almost completely dominate index performance while a massive tail of more than 2000 other ''opportunities'' go begging.

The net result is that since the most recent top in April last year, BHP has accounted for 38 per cent of the fall in the market and BHP, Rio, Newcrest, Woodside, Fortescue and Alumina, just six very unmagnificent resources stocks, have between them accounted for 72 per cent of the fall in the index and, if you want to push it out a bit further, just 20 stocks have accounted for 97 per cent of the fall in the market.

Looked at another way, 10 per cent of the stocks have dictated 100 per cent of the performance since the top of the market last year.

So before you use ''the market'' as an excuse for why you lost money in the past 16 months, you might ask yourself if the index actually has any relevance to what you do because the market indices in Australia are a lousy benchmark for an active self-managed super fund investor or trader, and an even more inequitable stick for a self-managed super fund investor's spouse or dependents to judge them by.

Anyone whose advice or performance is benchmarked to an index is compromised or compromises themselves because they end up being pressured into holding what has come to be known as the ''Moron Portfolio'', a portfolio of all the biggest stocks in the market: BHP, the big four banks, Telstra, Woolworths, Wesfarmers, Woodside, Rio and Westfield.

The unfortunate truth is this small group of stocks completely dominate the calculation of the Australian indices and anyone who wants to come close to the index has to hold them or advise you to hold them. We talk about bias reducing the value of analysis and advice. Well a bias to the biggest stocks in the market destroys it.

The interesting part of all this is that as an average 20-stock self-managed super fund portfolio investor, you have no reason to benchmark yourself. Why would you? But you do. You see the index as a yardstick. But the moment you start benchmarking yourself, even to a well distributed index let alone the ''rock in a sock'' indices we have to put up with here, you start to pervert the stock-picking process.

If you fear a spouse's, your dependents' or even your own expectations, you start to do things that distort the purity of your purpose, which is quite simply ''to pick the best investment in the whole world at any particular moment in time''.

To do that effectively you have to do it unencumbered by the need to pick stocks that help you perform like the index. If you're worrying about what someone is going to say, you have already lost. Choice and freedom have gone and anxiety and stress have crept in, to your detriment. It is not necessary.

Let the fund managers and the people that invest with them worry about their relative performance. If you are a self-managed super fund investor or trader, you have a lot of advantages over fund managers.

They include flexibility and speed. The ability to deal in anything at any time without the same liquidity constraints. But most of all they include operating without the pressure of clients looking over your shoulder and without having to perform relative to an assembly of big and occasionally rubbish stocks.

They can build an index but they can never take your freedom.

Marcus Padley is a stockbroker with Patersons Securities and the author of sharemarket newsletter Marcus Today. His views do not necessarily reflect the views of Patersons.