Just as house hunters are told, the three most important things are ''Location! Location! Location!", share investors are told ''Diversify! Diversify! Diversify!"

But diversification is easier said than done on the JSE. Most managed funds focus on the top 40 because the rest of the JSE's listings are too small and thinly traded.

Looking at the JSE, you would think we are a nation of miners.

But, according to Statistics SA's gross domestic product figures, we are a nation of bankers, followed by civil servants, factory workers and shop keepers. Miners are a distant fifth.

The big five resources shares - BHP Billiton, Anglo American, Sasol, Anglo Platinum and Anglo Gold Ashanti - alone account for a quarter of the R5-trillion combined market capitalisation of the 420 companies listed on the JSE.

This dominance of the JSE's miners results in the Satrix and Bips Top 40 exchange-traded funds, which track the JSE's blue chip market cap index, containing 45% basic materials. Resources reach half, once Sasol is added.

For investors who consider that too much heavy metal for a healthy investment diet, Bips offers an exchange-traded fund where each of the Top 40 is equally weighted. Satrix and Absa Capital also have several exchange-traded funds which track non-market cap indexes designed to cut down on resource shares.

For investors who want their share portfolio to reflect the ''real economy", GDP data seems a logical place to start.

The GDP data released on Tuesday shows manufacturing is growing, while mining is declining. Manufacturing surged 8%, while mining shrank 3% from the first to the second quarter.

This means that investors should be looking at more industrial shares and less resources, something that passive index-tracking funds are likely to start doing automatically.

At the time of writing, SAB had toppled Anglo American as the JSE's No3 company, placing the brewer behind British American Tobacco and BHP Billiton.

SAB's rise helped the JSE's broad industrial index made of about 100 companies nudge ahead of the 20 companies in the resources index.

Industrials and resources each account for about a third of the JSE's total market capitalisation.

Where the GDP and JSE market cap pie charts are severely out of kilter is financials: this is the biggest slice of GDP, while the financial index with its 40 companies have a combined weight of less than a fifth of the JSE's total market capitalisation.

The GDP's ''finance, real estate and business services" sector grew 1.6%, marking a rebound after two quarters of contraction.

In what economists call ''nominal prices" - ignoring inflation - SA produced a record R657-billion GDP at current prices over the April-to-June quarter.

That deflates to R456-billion, if the purchasing power is set to 2005 rands.

This means in ''real prices", our economy has not recovered to the R462-billion peak it reached in the fourth quarter of 2008.

One snag in using the GDP as an asset allocation template is Stats SA breaks the country's overall economy into 11 parts which are not that easy to reconcile with JSE sectors. For instance, you can't buy shares in SA's second-largest industry: general government services.

Government has proved itself to be recession proof.

This week's data for the second quarter placed government as SA's second-fastest growth industry after manufacturing at 4% quarter-on quarter.

Government has been clocking up higher than 4% growth for most of the past 14 quarters.