The 4 Biggest Mistakes UK Investors Make with Their SIPP

In the hundreds of SIPP portfolio reviews I have conducted through the Great Investments Programme, I see the same four mistakes repeated with remarkable consistency. They are not obscure errors that require deep financial expertise to understand. They are structural failures in how most self-directed investors approach their pension — and every one of them has a clear, practical fix.

The reason these mistakes persist is not a lack of intelligence among investors — GIP clients are executives, IT professionals, business owners, and finance professionals. The reason they persist is the absence of a system. Without an explicit, repeatable framework for what to buy, when to buy, how much to pay, and critically, when to sell, even analytically capable people default to the same behaviour patterns that cost them meaningful money over time.

Alpesh Patel OBE is a hedge fund manager, Bloomberg TV alumnus, Financial Times author, and former Visiting Fellow at Corpus Christi College, Oxford. This post is based directly on patterns identified across hundreds of GIP portfolio reviews.

Mistake 1: Leaving Money in the Default Fund

The most common and most costly mistake is the one that requires no action at all to make: doing nothing. Approximately 70–80% of UK defined contribution pension investors are invested in the default fund of their scheme — a managed multi-asset fund chosen by the scheme trustee as the standard allocation for members who never actively selected a fund.

In a GIP portfolio review context, I encounter versions of this mistake constantly. The investor has a self-directed SIPP — they have taken the first step. But inside the SIPP, the money is sitting in an HL ready-made portfolio, or a standard Vanguard LifeStrategy, or simply in cash because they opened the SIPP and then got distracted. The SIPP structure is right. The underlying investment is not being actively managed.

The cost: on a £200,000 pot over 15 years, the difference between a default multi-asset fund (7% net) and the GIP framework (13% net) is approximately £830,000. The default fund is not a rounding error. It is the single most expensive decision most pension investors never consciously make.

The fix: access the GIP Approved List and begin building a systematic portfolio of 20–25 positions that pass all five quantitative screens. This is precisely what the Great Investments Programme is designed to enable.

Mistake 2: Ignoring Platform and Fund Charges

The second mistake is treating charges as a minor technical detail rather than a compounding drag on returns. A 1.0% total charge on a £200,000 SIPP over 20 years at 10% gross return costs approximately £265,000 in foregone capital compared to a 0.15% charge on the same underlying return. This is not a marginal difference — it is a life-changing one.

In portfolio reviews, I find investors who have been paying 1.0–1.5% per year in combined platform and fund charges for 10–15 years without ever calculating what that has cost them. They see a number on their statement that has grown, they assume the strategy is working, and they never run the counterfactual of what the same capital would have returned at lower cost.

The fix: calculate your total annual cost of ownership today. Add the platform fee, the fund OCF, any adviser trail commission, and any dealing charges for your typical trading frequency. Compare to what is available on lower-cost platforms. If the total exceeds 0.5%, there is almost certainly a cheaper option available without sacrificing access to the investments you want.

Mistake 3: Not Consolidating Old Pension Pots

The average UK professional accumulates 11 pension pots over their working life. The Association of British Insurers estimates the value of lost and forgotten pension pots in the UK at over £26 billion. In GIP portfolio reviews, I routinely find that a client who considers themselves an engaged investor has two or three dormant pots from previous employers that they’ve vaguely tracked on annual statements but never actively managed.

The cost of this mistake is not just administrative inconvenience. Each unconsolidated pot is sitting in a default fund at its original scheme’s charges, growing at the default fund’s rate, and receiving none of the active management that the investor’s main SIPP is receiving. A £20,000 Nest pot at 6.5% net grows to approximately £51,000 over 15 years. The same £20,000 under the GIP framework grows to approximately £108,000. Across two or three dormant pots, this represents £100,000–£200,000 in foregone capital.

The fix: run the government’s Pension Tracing Service at gov.uk/find-pension-contact-details today. Identify every pot. Check for guaranteed annuity rates or early withdrawal charges. Transfer the unprotected ones to your primary SIPP.

Mistake 4: No Systematic Exit Criteria

The fourth and most psychologically interesting mistake is the absence of explicit exit criteria. Most self-directed investors have a reasonably clear entry process: they research a stock, read the investment case, and decide to buy. Almost none of them have an equally clear answer to the question: under what specific conditions will I sell this?

Without an explicit exit framework, two destructive behaviours dominate. The first is holding losers. Behavioural finance research by Shefrin and Statman (1985) — the disposition effect — shows that investors systematically hold losing positions too long and sell winning positions too early, because realising a loss feels worse than holding a paper loss. Investors rationalise a falling stock with ‘it will come back’ narratives instead of asking whether the quantitative case that justified the purchase still holds.

The second is selling winners prematurely. The same research shows investors tend to take profits on strong performers because the gain ‘feels real’ once crystallised — even if the quantitative case for holding remains fully intact.

The GIP fix is explicit. The exit criteria are:

• A stock drops off the GIP Approved List because it no longer passes one or more of the five quantitative screens. This is the primary systematic exit trigger — independent of price movement.

• Monthly MACD crosses below its signal line (Mommy Bear signal). A deteriorating price trend signal that triggers a review of the position.

• A position grows beyond 8% of portfolio weight. Trim to target weight at quarterly review. This is not a sell signal — it is a discipline mechanism that enforces selling into strength.

The most important thing about exit criteria is that they are defined before the emotional situation arises. A falling stock is the worst time to decide whether to hold or sell. The decision framework must exist before the stock starts falling.

If you recognise any of these four mistakes in your current portfolio, a GIP portfolio review will map them explicitly and show you the practical steps to address each one. Book a free portfolio review here.

Sources & Further Reading

Shefrin, H. & Statman, M. (1985) — ‘The Disposition to Sell Winners Too Early and Ride Losers Too Long’. Journal of Finance. Foundational research on the disposition effect in investor behaviour. onlinelibrary.wiley.com

Association of British Insurers — Data on lost and dormant pension pots in the UK. abi.org.uk

DALBAR — Quantitative Analysis of Investor Behaviour (QAIB). Annual research on investor timing errors and behavioural costs. dalbar.com

Financial Conduct Authority — Workplace pension default fund governance and charge cap rules. fca.org.uk

Financial Times — Behavioural finance, investor errors, and the case for systematic investing. ft.com/investing

Disclaimer: This article is for educational purposes only and does not constitute personal financial guidance. All investing carries risk. Past performance is not a reliable indicator of future results.

Alpesh Patel OBE

www.campaignforamillion.com