Bonds are often treated as the safe, defensive part of a portfolio, but that description can hide an important distinction. A short-duration government bond fund and a long-duration gilt fund are not simply different versions of the same thing; they can behave very differently when interest rates move. Duration is the key measure: the longer the duration, the more sensitive the bond’s price is to changes in yields.

The experience of long-dated gilts in 2022 showed this clearly. Rising yields led to large falls in long-duration bond funds, with losses that looked much closer to equity-market drawdowns than many investors would expect from ‘safe’ assets. This does not mean long-duration bonds are bad, but it does mean investors need to be clear about the role bonds are meant to play. For capital preservation, spending needs and portfolio stability, shorter-duration bonds may be better aligned with the job investors usually expect their defensive assets to do.

Complex investment strategies are not necessarily bad, but they often make risk harder to see and understand. A 3x leveraged S&P 500 strategy can look attractive in a strong decade, yet it is not simply ‘the S&P 500, but more of it’. It is a financed derivative position where gains, losses, costs and behavioural pressure are all magnified.

The real test is not whether equities rise over the long term, but whether the strategy can survive the period. Financing costs can materially reduce returns, drawdowns can become intolerable, and a bad decade can wipe out the investor before any recovery arrives. For most long-term investors, simplicity is not a weakness; it is often what allows them to stay invested.

Indexing is not ‘breaking’ markets simply because passive funds own a growing share of them. Prices are set by trading, not by ownership, and active investors still do the vast majority of price discovery. That means the key question is not how much of the market is indexed, but whether enough active capital remains to keep prices tied to fundamentals.

Even if passive investing did begin to create distortions, those mispricings would themselves attract active managers seeking profit. In that sense, the system is partly self-correcting. Rather than destroying market efficiency, the rise of indexing may simply be pushing out weaker active managers whilst leaving enough skilled investors in place to keep markets broadly efficient.

Recent debate about the US equity market has focused on two related facts: a small group of mega-cap stocks has driven a large share of recent index returns, and those same firms now make up a large share of the index itself. But those are not quite the same issue. Concentration tells us how the market is weighted. Valuation tells us what investors are paying for future cash flows. That distinction matters, because valuation is the more direct link to long-run expected returns.

The evidence suggests that concentration on its own is a weak guide to future market returns. Markets have been highly concentrated before, both in the US and abroad, without that reliably leading to poor outcomes for the market as a whole. The more persuasive concern is that dominant stocks often struggle to sustain exceptional outperformance once they have reached the top, and that elevated starting valuations have historically been associated with lower long-horizon returns. So the real question is not whether the market looks concentrated, but whether current prices already assume too much good news.