A Diversification Trap To Avoid

Published in Investing Strategy on 6 November 2009

Many investors mistakenly believe their portfolio is properly diversified.

I'm a big fan of diversification -- which is why a fair sized proportion of my wealth is tied up in the most diversified UK-based investment you can get -- a FTSE All-Share index tracker. And, in the true spirit of diversification, with not just one tracker provider but three.

To some investors, diversification has a significant downside. There's an inverse relationship between risk and reward, they point out, and the more concentrated your portfolio, the more you'll benefit from an individual company's growing share price.

That is, of course, true. But by diversifying so broadly, I'm also protected -- as far as I can be -- from an individual company's declining share price. If I'd had a significant proportion of my wealth invested in Royal Bank of Scotland (LSE: RBS), for example, I'd be feeling pretty gutted right now.

Sector simplicity

I do invest in individual companies, of course. And have done so for years. But these days, my aim is to make sure that those companies are as diversified as possible. And it's an objective that has led me to mull over what diversification actually means.

What it doesn't mean is simply 'sector' or (worse) 'sub-sector' diversification. Yes, you wouldn't want all your eggs in the same sector -- engineering companies, for example, or retailers, or (heaven forbid) banks. But blindly spreading investments across sectors has its dangers, too.

Back in 2007, for instance, there were investors over on the High Yield Portfolio board arguing that to be invested in both HBOS and Northern Rock was being diversified: one was a High Street and business bank; the other a mortgage bank. Shortly thereafter, as we all know, the wheels came off that particular piece of logic with spectacular (and wealth-destroying) consequences.

Equally, diversification doesn't mean splitting your portfolio between (say) a bank, a house builder and a commercial property fund. As the last eighteen months have shown, they are both exposed far too much to the twin vicissitudes of the financial and property markets. They're in different sectors, certainly, but linked by common themes.

Different strokes

So true diversification involves spreading risk much more widely than simply across market sectors or sub-sectors which may, in the event, turn out to be chillingly correlated.

It involves investing in companies that sell different products in different markets, to different customer groups, and which are exposed to different economic cycles and financing pressures. And that's just for starters.

So, following this logic, and picking some large-caps at random, is an investment in Marks & Spencer (LSE: MKS) and Unilever (LSE: ULVR) diversified? Not really: there's a common over-exposure to affluent consumers, moderated only by the latter's developing world exposure.

How about Marks & Spencer and Cadbury (LSE: CBRY), then? No: that carries an over-exposure to consumers, full stop. What about Marks & Spencer and BAE Systems (LSE: BA)? Ah, now we're talking: different products, different markets, different customer groups, different economic cycles. You get the picture.

Questions to ask

So what is a good test of diversification? Here are some questions to ask, and points to ponder. They're not a definitive list, I'm sure, but a very good starting point. Do you have a favourite diversification test? If so, tell us about it in the box below.

  • Who are the customers, and what pressures drive them?
  • Are sales defensive, or discretionary?
  • How internationally diversified are those sales?
  • Are there lots of customers, or just a few?
  • How diverse are the sources of funding?
  • What drives the business cycle?
  • Is there a common supply risk?

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Comments

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rober00 06 Nov 2009 , 5:01pm

Malcolm I am afraid I would not call owning the FTSE All Share index diversified!!!

80% of its value consists of companies in the FTSE 100 and of course the FTSE 100 is dominated by 6 companies itself.

lotontech 06 Nov 2009 , 6:58pm

Malcolm,

You may of may not agree with me that true diversification also involves spreading risk "over time".

If you diversify a lump sum all-at-once in perfectly uncorrelated assets then as some assets go up then the others go down to compensate. Great for satisfying investment rule #1 : "DON'T LOSE MONEY" but not so great for making money.

As a simple example of diversifying over time:

Why not buy out-of-favour assets today with half (or less) of the cash, and keep the other half (or more) cash on hand until the uncorrelated assets fall out of favour and the currently held assets have appreciated in sympathy? Once you are fully invested you will have your risk-free perfectly-uncorrelated portfolio but with some profit "locked in".

(easier said than done, of course)

Even something as diversified as the FTSE All-Share Index -- rober's comment notwithstanding -- can fall in double-digit percentages, which is why some people recommend "pound cost averaging" as a way to buy more units when prices are low and fewer units when prices are high by making regular contributions. Again, this adds a "time" element to the diversification.

What do you think?

Tony Loton

MDW1954 06 Nov 2009 , 7:00pm

I'm sorry, I suppose the term "fair sized" is a bit glib -- it wasn't my intention to mislead!

Of course, as detailed in previous articles here on the Fool, I've got holdings in Asia Pacific funds, a mining and exploration fund, a oil exploration fund, and a FTSE-250 fund. I've not previously mentioned a fairly hefty Vanguard "developed world excluding UK" tracker, but that exists, too.

Apologies.

Malcolm Wheatley (author)

MDW1954 06 Nov 2009 , 7:03pm

Tony,

I agree with your observation about pound-cost averaging time-based diversification.

I'm sure I agree with the other point, too -- it's just that I'm not clever enough to do it!

I hope you and your family are keeping well.

Malcolm


Luniversal 07 Nov 2009 , 9:52am

"Back in 2007, for instance, there were investors over on the High Yield Portfolio board arguing that to be invested in both HBOS and Northern Rock was being diversified: one was a High Street and business bank; the other a mortgage bank."

Er... not just 'investors', Malcolm. The distinction originated with your esteemed contributor TMFPyad himself, sole begetter of the High Yield Portfolio system, and some time earlier than 2007 at that.

Iniq 09 Nov 2009 , 2:27pm
Iniq 09 Nov 2009 , 2:36pm

Lotontech: Yes, I too am a great believer in pound-cost-averaging when investing. However there is one aspect which many people overlook.

When you come to dis-invest (as I plan to as I get older, and will seek the reduced volatility of cash and/or gilts), if you do not wish to undo all the benefits of pound-cost averaging, it's important to sell a fixed NUMBER of shares/units each month, not a fixed £'s worth each month.

This gives you pound-cost-averaging in reverse, so that you end up selling a greater £'s worth of shares when the price is high and less when it's lower. If you make the mistake of selling an equal £'s worth each month, you end up selling MORE shares when their price is low and fewer when the price is high. Think about it ...

lotontech 09 Nov 2009 , 3:04pm

Hi Iniq,

Yours is the most insightful comment I have read for a long time in a forum like this one :-)

Thanks for adding it to my original point about Pound Cost Averaging.

Tony.

gordonbanks42 09 Nov 2009 , 4:20pm

Re pound cost averaging (into and out of equities): I think this is not the first time Iniq has raised the point about exit strategy, and I too am grateful for the observation.

This is surely only possible if you are keeping, or planning to keep, significant value somewhere other than in equities (e.g. cash), which in turn is a form of diversification between asset classes. Hence I see it as a tactic (and a very crafty one) to accompany strategic asset allocation.

More generally, for me the big lesson of the last couple of years is that the degree of correlation between one investment and another is not a fixed property of that pair of investments. It depends on the circumstances, and how serious they are. Perhaps there is a rule of thumb which says (for a broad spectrum of investments) "the more dire the circumstances, the more correlated things get". One might draw a (somewhat fanciful) analogy with international relations - most of the time India and Pakistan are doing their best to counter each others' efforts, as are Israel and Iran, etc. etc. If Mars attacked, one might hope they would bury their differences, at least for a while.

If that's the case, perhaps we need some idea of layering to our diversification - "shallow" diversification, where low (or negative) correlation survives run-of-the mill adversities, and "deep" diversification, which is designed to survive even the more serious and (hopefully) less frequent events.

Identifying the latter effectively will presumably require thought about how things in the world actually work, and how they might break (which change over time), not just an expert understanding of backward-looking correlation stats. Not so easy.

gordonbanks42 09 Nov 2009 , 4:26pm

My contribution to the draft list of diversification tests:

"What kind of event would take these down together?"

It's vaguer than the others, but I would suggest that there is merit in that, too.

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