While it’s commonplace for investors to hold multiple investments in a portfolio – often comprised of mutual funds or ETFs that in turn hold dozens or even hundreds of underlying positions – the reality is that even multi-asset-class portfolios aren’t always really diversified.
The fundamental problem is that holding many different investments that are all aligned to the same “base case” market scenario – and all go up together – may be equally at risk to decline together if an adverse event happens instead.
For instance, a “well diversified” portfolio holding US stocks, emerging markets, commodities, and corporate bonds, may be invested into multiple asset classes – but they would all be expected to go up in a growth environment, and all would likely decline severely in a recession!
Of course, the investments that don’t go down in a recession, from “defensive” stocks to government bonds, are also the investments likely to perform the worst if markets continue to rise. But in the end, that’s the whole point of diversification – to own investments that will defend in the risky events, even if it means giving up some upside in the process. Or viewed another way, being well diversified means always having to say you’re sorry about some investment that’s not moving in the same direction as the rest!
And given the complexity of today’s investment environment, and the typical multi-asset-class portfolio, a growing range of tools are becoming available to “stress test” various risky scenarios, to help determine whether a portfolio is truly diversified, or just holds a large number of investments that are all expected to go up – and down – in an undiversified manner!