Index funds: the 5% you can lose in three days

Index funds won't spare you a 5% drop in three days

There is no index fund that guarantees inflation-beating returns while preventing a 5% loss in three days. That is the unavoidable conclusion when someone asks for a conservative, cheap product that doesn't require watching the screen every day. The answer is stubborn: any vehicle aiming to beat inflation takes on volatility, and those who can't tolerate it should reconsider their initial investment, not the product. The episode offers a snapshot of a debate that goes far beyond one specific fund: what an index fund really is, who pockets the fees, and why so many people confuse investing with gambling.

What an index fund is and what it isn't

An index fund replicates an index — the MSCI World, the S&P 500 — by buying the stocks that make it up in the proportions the index sets. There is no manager getting it right or wrong: there is a financial architecture behind it, that of providers like Vanguard, Amundi or BlackRock, which structures the product. The most common misconception is believing you can "do it yourself" by buying the 500 largest S&P 500 companies piecemeal. That is not replicating an index: it's a homemade portfolio with broker fees and no rebalancing.

That's where the intermediary comes in. Platforms that package portfolios according to risk profile are not competitors of Vanguard or BlackRock: they are a service that automates purchases and rebalancing. The value they add is saving you work, not manufacturing returns. And that comes at a price, on top of the underlying fund's fees.

The fee argument: fund vs ETF

The sharpest criticism targets cost. If an index fund holds S&P 500 and MSCI World ETFs that anyone can buy for a minimal annual fee, why pay triple? The answer has two tax legs and one operational one. In Spain, funds allow you to transfer money between funds without going through the tax authorities; ETFs force you to sell and pay capital gains tax. In exchange, ETFs trade in real time while funds take days to execute an order.

The rebalancing debate also divides opinion. Some consider it essential to maintain the risk profile, others dismiss it as unnecessary noise in a 15 or 20-year strategy. The evidence cited in the discussion is that most actively managed funds fail to beat their benchmark index, and that an MSCI World with regular contributions is enough to let you sleep soundly.

The fine print of bonds

Consensus breaks down when bonds come up. The dominant thesis in the discussion is that medium and long-term fixed income is in a bubble inflated by central banks, and that once stimulus is withdrawn and debt purchases slow down, bond funds will have a hard time. Hence the recommendation to keep bonds out of a portfolio meant to be conservative, even though the classic rulebook says otherwise: the stock-bond split based on age and time horizon.

The alternative proposed for cautious investors is different: reduce the initial amount. If losing 160 euros out of 11,000 keeps you up at night, starting with 3,000 and contributing 1,000 or 1,500 a month lets you test your real risk tolerance without betting your entire wealth at once.

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The underlying question is not whether index funds carry risk — they do, like any asset — but how much risk the buyer's mind can take. With an MSCI World and monthly contributions, the most likely scenario over a decade is reasonable. With the same portfolio and a weak stomach, selling at the first drop is guaranteed.