Why Some Apps Show Live Share Prices — and Others Don't

TL;DR: The difference is mostly about who's paying. Real-time, "streaming" prices come straight from the exchange and cost money to license, so brokers and paid terminals buy that feed for you. Free, no-account sites usually show a legally mandated delayed feed — up to 15 minutes behind — because that's the free version the rules require exchanges to offer. The rest comes down to how well an app is engineered to handle a fast-moving feed without breaking.

What "live price" actually means

A share price isn't broadcast on a schedule. It only exists the moment a buyer and a seller agree on a number and a trade clears on the exchange. Everything you see afterwards — on a broker's app, a news site, a random price-checker — is a copy of that moment, passed along a chain. How long that copy takes to reach you is the whole story.

The trade happens on the exchange first

Every listed share trades through an official exchange, which is the single source of truth for its price. The exchange doesn't just match buyers and sellers; it also packages up every trade and quote into a data feed and sells access to that feed — you can see this split between live and delayed access laid out directly on the London Stock Exchange's market data page. That's the raw material every app, website and broker is working from — nobody has a "more accurate" price than the exchange itself, only a faster or slower copy of it.

The 15-minute delay rule most free sites use

In the UK and EU, exchanges can't simply lock real-time data behind a paywall forever. Under the EU's MiFID II market-data rules, trading venues are required to make their data available free of charge no later than 15 minutes after publication. That's not a technical limit or a broker trick — it's a regulatory floor. Plenty of free finance sites simply build around that rule: they take the free, delayed feed rather than pay for the instant one.

Why your broker's app is live but a random website isn't

This is the part that confuses most people, because it looks inconsistent. The same company's share can show "delayed" on one tab and update instantly on another, and the gap isn't about which app is better designed — it's about which one is paying.

Who pays for real-time data, and why it isn't free

Streaming, real-time prices are a licensed product. Exchanges sell that feed to brokers, trading platforms and financial terminals, who in turn fold the cost into your account or subscription. When you open your broker's app and watch a price tick, you're looking at data the broker paid for on your behalf, specifically because you're a customer actively trading or watching that market. A free comparison site, with no account and no revenue tied to a specific trade, generally has no business reason to pay that bill — so it takes the version the rules say must be free instead.

Free "delayed" view vs paid "streaming" view

	Delayed (free)	Streaming (live)
Who pays	No one — the exchange provides it free by rule	The broker or platform, via a paid data licence
Typical lag	Up to 15 minutes behind the exchange	Near-instant, usually under a second
Where you'll see it	Most free finance and news sites	Broker apps, trading platforms, professional terminals
Good enough for	Checking how a company or the market is generally doing	Placing or timing an actual trade

How a price actually gets from the exchange to your phone

Even once an app has the right to real-time data, getting it onto your screen reliably is its own engineering problem — separate from the data licence entirely.

Market data feeds and streaming APIs

Live prices aren't fetched by the app repeatedly asking "has it changed yet?" — that would be slow and would hammer the exchange's servers. Instead, modern apps hold a persistent connection open and let the exchange's data feed push updates down it the instant a trade happens, the same way a messaging app gets your texts the second they're sent rather than checking for them every few seconds. It's the difference between a static page you have to manually refresh and one that updates itself in front of you.

Why this is a real software engineering problem

Keeping that connection alive, accurate and fast is harder than it sounds. Mobile networks drop out on the Tube, in lifts, between Wi-Fi and mobile data — so the app has to detect the break and reconnect without you noticing or seeing a stale price frozen on screen. During a busy trading session, a popular share can update hundreds of times a minute, and the app has to redraw the number smoothly without the interface stuttering or the battery draining in an hour.

There's also a quieter trade-off happening underneath all of this: keeping a connection permanently open and redrawing a number on screen that often costs real battery and real data. A well-built app throttles how often it actually repaints the screen, pauses the stream when you switch to another tab, and reconnects gracefully rather than showing an error the moment a signal flickers. Get any of that wrong and the price either lags anyway, or the app drains your battery trying to stay current. None of it happens by accident; it's deliberate, careful mobile engineering, which is exactly the kind of problem a mobile development team that knows how to keep a live data feed from crashing the app is built to solve.

Does the Student Investor Challenge use live prices?

Within the Challenge itself, different parts of the game are built around different kinds of pricing, on purpose. Your standing against other teams updates in real time: your ranking is calculated continuously and shown on the portfolio league table, so you can check where you stand whenever you like. The semi-final stage works differently again — as set out in the semi-final rules, teams predict the Friday closing price of selected assets rather than reacting to a live tick. That's a deliberate format for testing judgement over a week, not a technical limitation.

Does a few minutes' delay actually matter for your decisions?

For almost everything you'll do as a learner, no. If you're reading a chart to understand how volatile a share has been, checking whether a company's results moved the market, or deciding whether a business looks interesting over the long run, a price that's a few minutes old tells you essentially the same story as one that's live to the second. The gap only starts to matter if you're trying to execute a trade at a precise moment — and the Challenge isn't about reacting in real time to the exact tick; it's about building the judgement to read a market sensibly in the first place.

This article is educational and is not financial advice. Regulatory detail on free delayed market data is drawn from the EU's MiFID II/MiFIR framework (ESMA final report, Article 13(1)); exchange data-licensing context from the London Stock Exchange's own market data pages.