Order execution time — why quality matters more than the spread

Welcome. You click "buy" at 1.0850, convinced that this is the price you will get. Yet between the click and the line in your account history sits a whole chain of events that lasts fractions of a second and can decide whether your price is 1.0850 or already 1.0853. That chain is what we call order execution. In this piece I explain what it is made of, where slippage comes from, and why execution quality alone often matters more than the spread a broker advertises.

What "order execution" actually means

Execution is not a single instant but a sequence of steps. Your click becomes a network message and travels to the broker's server. There the order is accepted, the broker sets the execution price and, in a market model, asks a liquidity provider for it. The trade is struck, the price fixed, and the confirmation returns along the same route to your platform, which only now shows "executed". Each of these legs takes milliseconds, but they add up.

It helps to separate two ideas that are easy to confuse. Network latency is the round-trip travel time of the data — it depends on distance and on the quality of the connection. Broker processing time is what happens on the server itself: the risk check, the choice of price, the possible decision to hedge the position. The execution chain is therefore only as fast as its slowest link, and that link decides whether you get the price you saw on screen.

Instant execution versus market execution

Platforms usually offer two modes, and they differ in where the uncertainty is hidden. Under instant execution you send the order at the price shown on screen. If the market is exactly there, you get that price. If it has already moved, the broker returns a requote — a fresh offer you must accept or reject. You have certainty of price, but no certainty that you will get in at all.

Market execution is the reverse. You accept the best available price in advance, so the fill is effectively certain, but slippage may appear — a deviation of the execution price from the one you saw. Slippage cuts both ways: sometimes against you, sometimes in your favour. That is why scalpers and news traders most often choose market execution. In a fast market a run of requotes can throw you out of a good entry entirely, and certainty of the fill is often worth more than a single pip. I unpack the deviation mechanism itself in the piece on what slippage is.

What affects execution time and quality

Execution is built from several layers, and you influence them to different degrees. The first is the broker model. At an ECN broker the price comes straight from liquidity providers, with the intermediary merely relaying it. It is worth knowing that some liquidity providers use a last-look mechanism — the right to reject an order after it has been submitted, before it is filled. At a market maker the broker is the other side of the trade and has its own logic: a risk assessment, a hedging decision, sometimes a widening of the spread in a nervous moment. There is also a model in which a broker routes orders to specific liquidity providers in exchange for payment — that is how PFOF (payment for order flow) works. I describe the contrast between these two worlds in the comparison of ECN versus market maker.

The second layer is infrastructure. Brokers keep their servers in specialised data centres (Equinix in London or New York, for example), and some traders rent a VPS there to shorten the order's journey. The third layer is volatility and liquidity — on a quiet afternoon the book is deep and fills are smooth, while in the second of a major release liquidity briefly disappears. The fourth is your own connection and computer, the most under-rated link of all. The same conditions that spoil execution quality are sometimes exploited by the mechanics of stop hunting in a thin market.

Example: slippage on a post-news spike

I will use purely illustrative numbers to show the mechanism — these are not figures from a specific account. Imagine a trader entering EUR/USD in the very second of a US payrolls release.

On a one standard lot position, five pips on EUR/USD is roughly fifty dollars of difference against the screen price. For a swing trader chasing a move worth a hundred or two hundred pips, that is noise that does not change the picture. For a scalper aiming at a few pips, the same slippage can turn a profitable plan into a losing one. This is exactly why execution quality means something quite different depending on style, rather than being one number that suits everyone.

"An investment firm shall take all sufficient steps to obtain, when executing orders, the best possible result for their clients taking into account price, costs, speed, likelihood of execution and settlement." — MiFID II, Directive 2014/65/EU, Article 27(1), 2014

Why execution quality can matter more than the spread

The spread is visible at a glance and easy to advertise. Execution quality is less eye-catching and can cost more. A headline spread near zero means little if every market entry loses you half a pip to slippage, and more in nervous moments. What counts is the total cost of the trade: spread, commission and slippage together. How to break those elements apart I show in the piece on when the spread is cheaper and when the commission is.

Regulators see it the same way. The best-execution principle in MiFID II does not speak of price alone — it lists costs, speed and likelihood of execution alongside it as equal criteria. That is a good map for a retail trader too: judge a broker on the whole package, not on a single figure from a banner.

Demo versus a live account

A demo account can be misleading precisely on the subject of execution. On a practice account orders often fill perfectly, because you are not competing for real liquidity and nobody is hedging your position. On a live account you meet a real order book, real requotes and slippage in hot moments. Treat demo numbers as a rough guide, not a promise. If you are moving from practice to live trading, expect execution quality to be slightly worse — and test it with small size before you scale up your positions.

How to measure execution yourself

The best data is your own, not the advertisement. In MetaTrader open the journal (View → Toolbox → Journal). Every order carries a send and an execution timestamp, and the gap between them is your real execution time. Collect a few dozen trades and take the median, because a single record proves nothing. Then look at slippage: set the price at your click against the fill price and check whether the deviations are roughly symmetric or stubbornly against you. Finally, reach for the documents — EU brokers published best-execution reports required under MiFID II, whose status is changing as the rules are reviewed. For the broader principle behind choosing a regulated broker, see the section on choosing a broker.

What to do about your execution

1. Measure the median, not a single case. Pull a few dozen recent trades from the platform journal and work out your typical execution time and typical slippage. Only that number says anything about your account.
2. Check whether slippage is symmetric. If deviations regularly fall only against you, treat it as a warning sign and compare results with another broker on small size.
3. Match the mode to your style. For fast trading, market execution with accepted slippage is usually more comfortable; where reaction time is not critical, consider pending orders that fill when price reaches the level.
4. Count the total cost. Add spread, commission and slippage together rather than comparing brokers on the headline spread alone — that is the only honest measure of the real cost of a trade.