The £620 Leak Nobody Talks About
UK retail investors have become savvy about fund fees. They hunt for the lowest OCF (ongoing charges figure), compare platform fees down to the penny, and religiously track expense ratios. Yet most remain completely blind to a cost that can dwarf all of these combined: the bid-ask spread.
For a typical UK investor trading £20,000 worth of ETFs across their ISA annually, the cumulative spread cost can reach £620 per year. That's more than three times the annual fee charged by most discount platforms, yet it's virtually invisible in your account statements.
What Is the Bid-Ask Spread?
Every time you buy or sell an ETF, you're not trading directly with the fund company. Instead, you're trading with market makers who quote two prices: the bid (what they'll pay to buy from you) and the ask (what they'll charge to sell to you). The difference between these prices is the spread.
For example, if the SPDR S&P 500 ETF (SPY5) shows a bid of £385.20 and an ask of £385.80, the spread is £0.60 or roughly 0.15%. On a £5,000 purchase, you're paying an immediate £7.50 premium before the ETF even moves.
The Worst Offenders in UK ISAs
Popular ETFs available to UK retail investors show dramatically different spread patterns. Based on analysis of typical trading hours:
Widest Spreads (Highest Cost):
- Emerging market ETFs: 0.20-0.40%
- Small-cap regional funds: 0.15-0.30%
- Sector-specific ETFs: 0.10-0.25%
- Currency-hedged versions: 0.08-0.20%
Tightest Spreads (Lowest Cost):
- FTSE 100 trackers: 0.02-0.05%
- S&P 500 ETFs: 0.03-0.08%
- Large developed market funds: 0.04-0.10%
The difference matters enormously. An investor buying £2,000 of an emerging market ETF with a 0.30% spread pays £6 immediately, while someone purchasing the same amount of a FTSE 100 tracker with a 0.03% spread pays just 60p.
Platform-Specific Impact
Your choice of broker significantly affects spread costs:
Trading 212 and Freetrade users face the quoted spread with no additional markup, but their order execution during volatile periods can be slower, potentially widening effective spreads.
Interactive Investor and AJ Bell typically offer better execution speeds during market hours, though their fixed dealing charges can offset spread savings on smaller trades.
Hargreaves Lansdown adds a 0.45% dealing charge on top of the spread for online ETF trades, making spread optimisation less critical but overall costs higher.
Timing Your Trades
Spreads fluctuate dramatically throughout the trading day. UK investors can minimise costs by avoiding these expensive periods:
Worst Times (Widest Spreads):
- Market open (8:00-8:30 AM GMT)
- Lunch period (12:00-1:00 PM GMT)
- Final 30 minutes before close
- During major economic announcements
Best Times (Tightest Spreads):
- Mid-morning (10:00-11:30 AM GMT)
- Mid-afternoon (2:30-3:30 PM GMT)
- When both London and US markets are active
The £620 Annual Calculation
Here's how a typical UK ISA investor accumulates spread costs:
- Monthly investment: £1,667 (£20,000 annually)
- Average spread on mixed ETF portfolio: 0.12%
- Cost per trade: £2.00
- Annual spread cost: £24 × 12 = £288
Add rebalancing (quarterly), emergency sales, and dividend reinvestment trades, and the total easily exceeds £400 for conservative investors. Active traders or those favouring niche ETFs can hit £620 or more.
Practical Damage Limitation
Choose Your ETFs Wisely: Favour large, liquid funds over niche alternatives where the spread penalty exceeds the potential performance benefit.
Batch Your Orders: Instead of monthly £500 investments, consider quarterly £1,500 purchases to reduce trading frequency.
Use Limit Orders: Set your maximum purchase price rather than accepting market rates, especially for larger trades above £1,000.
Monitor Real-Time Quotes: Check spreads before trading. If unusually wide, wait 30 minutes and check again.
What to Watch Next Month
The Bank of England's next rate decision could trigger wider spreads across bond ETFs as market makers adjust for volatility. Similarly, any escalation in global trade tensions typically widens spreads on international equity funds.
Monitor your most-traded ETFs' typical spread ranges and avoid trading during known volatility events unless absolutely necessary.
The Bottom Line
While you can't eliminate bid-ask spreads entirely, awareness and timing can cut your annual cost by 60-70%. For most UK investors, that's worth more than switching to a cheaper platform or chasing marginally lower fund fees.
This article is for informational purposes only and does not constitute financial advice. Your capital is at risk. Past performance is not a reliable indicator of future results.