Choosing an investment platform

A platform is where you buy and hold. Research is how you decide what to buy. Most guides conflate the two — here's what actually separates platforms, and why this decision matters less than people think.

By Nathan Wickham-Hurd · Founder, Oak Growth · First-class Economics & Finance, MBA · Last reviewed August 2026

Disclosure, and an important distinction. Oak Growth is research, not a broker — you can't buy shares through it. This page is about the platforms you actually buy through, none of which I have any connection to. Fees and features change; check before opening an account.

The short answer

You need two different things, and most articles conflate them. A platform is where you hold and buy investments — the account, the wrapper, the dealing. Research is how you decide what to buy. Choosing a platform on its research tools is a mistake; choose it on cost and coverage, then get research separately.

What actually separates platforms

Fee structure, which flips with balance size

Percentage fees suit smaller portfolios and get expensive as you grow. Flat monthly fees are the reverse — painful on £2,000, excellent on £150,000. There's a crossover point, and working out roughly where yours sits matters more than any feature.

Dealing charges, especially if you invest monthly

A £10 charge on a £100 monthly purchase is a 10% loss before you start. Several platforms offer free or heavily discounted regular investing — that alone can outweigh a higher annual fee.

Which wrappers they offer

Stocks and shares ISA, SIPP, general account, Lifetime ISA, Junior ISA. Not every platform offers all of them, and the wrapper matters more to your long-run return than the platform does — see the ISA explained.

What you can actually hold

Some are funds-only. Some carry UK and US shares but little of Europe or Asia. Some carry investment trusts and ETCs, some don't. If you want a specific holding, check it's on their list before opening the account.

Foreign exchange charges

Buying US shares means converting currency. FX fees range from around 0.15% to 1.5%, and on a US-heavy portfolio that's a larger cost than the platform fee. It's usually buried in the small print.

A rough rule that survives most comparisons: under roughly £20,000, a percentage-fee platform with free regular investing usually wins. Above roughly £50,000, a flat-fee platform usually does. In between, it depends on how often you trade.

The main UK platforms

Broadly, they fall into three groups. Full-service platforms — Hargreaves Lansdown, AJ Bell, interactive investor — offer every wrapper, wide investment choice, phone support and research, at higher cost. Low-cost app-based platforms — Trading 212, InvestEngine, Freetrade — are cheaper, often with commission-free dealing, with narrower choice and less support. Fund houses like Vanguard are cheapest of all if you only want their own funds, and useless if you want individual shares.

I'm deliberately not ranking them, because the right answer genuinely depends on your balance, what you hold and how often you buy — and because fee schedules change often enough that any ranking published today would be stale within months. Compare current rates on each provider's own site, and check they're covered by the Financial Services Compensation Scheme.

The part most guides skip

The platform decision is worth getting roughly right and then forgetting. The difference between a good platform and a great one might be 0.3% a year. The difference between buying a business worth more than you paid and one worth less is orders of magnitude larger.

Put differently: the platform is the shop. What you put in the basket matters more than which shop you're standing in. That's the gap research fills — knowing what a company is actually worth before you buy it, which no platform's built-in tools will tell you.

What to check before opening an account

FSCS protection

Up to £85,000 per firm if the provider fails. Confirm the entity you're signing up to is covered.

The total annual cost on your balance

Platform fee plus fund charges plus dealing plus FX. Most people compare only the first.

Transfer terms

Some charge to move your holdings out. Worth knowing before you're locked in.

Whether they offer the wrapper you need

If you want a SIPP later, easier to start somewhere that offers one.

The platform is the shop. This is the shopping list.

Oak Growth estimates what roughly 1,000 companies across eight markets are worth and shows the gap against today's price — whichever platform you buy through.

Explore Oak Growth

Common questions

What is the best investment platform in the UK?

It depends mainly on your balance and how often you buy. Percentage-fee platforms generally suit smaller portfolios, flat-fee platforms larger ones, with a crossover somewhere between £20,000 and £50,000. Dealing charges matter enormously if you invest monthly, and FX fees matter if you hold US shares.

Is Oak Growth an investment platform?

No. Oak Growth is research — it estimates what companies are worth and scores them on moat, management, economics and value. You cannot buy shares through it. You would use it alongside a broker such as any of the main UK platforms, not instead of one.

What fees should I look for on an investment platform?

Four, not one: the annual platform fee, the charges on any funds you hold, dealing costs per trade, and foreign exchange fees on overseas shares. FX in particular ranges from about 0.15% to 1.5% and on a US-heavy portfolio can exceed the platform fee itself.

Does the choice of platform matter much?

Less than people assume. The difference between a good and a great platform might be around 0.3% a year. The difference between buying a business worth more than you paid and one worth less is far larger, which is why research deserves more attention than the platform decision does.

Also see: How to buy shares in the UK → · Stocks and shares ISA explained → · The best stock screeners →