Manual traders obsess over entry signals — and then send their order straight to market like it's a pizza delivery request. What actually happens between clicking "buy" and the fill arriving is where a surprising amount of return gets quietly destroyed. Slippage, spread, market impact: these are the silent costs that backtesters conveniently forget to model.

Algorithmic systems treat execution as a first-class problem. Rather than routing blindly to a single venue, a well-designed algo evaluates available liquidity across multiple exchanges and dark pools, timing the order to minimise market impact. The difference between a naive market order and an intelligently routed one can be measured in basis points — which, compounded across thousands of trades, adds up fast.

CONCEPTSmart order routing disaggregates liquidity across venues to find the best available fill — not just the best quoted price.
WARNINGOptimising your entry signal while ignoring execution quality is like tuning an engine and forgetting to check the tyres.
KEY IDEAImplementation shortfall — the gap between your decision price and your actual fill — is the most honest measure of execution performance.

Implementation shortfall is the metric serious execution desks watch obsessively. It captures the full cost of trading: delay, market impact, and missed trades. A backtest might show 18% annualised returns, but if your implementation shortfall runs at 15 basis points per trade across 500 trades a year, you've just handed back a material chunk of edge before fees are even considered. This is the gap that makes traders question their life choices.

Execution Cost by Order Type (basis points)MarketLimitSOR~18bp~11bp~6bpCost (bp)

Smart order routing algorithms typically consider price, venue fees, fill probability, and queue position simultaneously. Some incorporate predictive models of short-term price movement to decide whether to be passive or aggressive at any given moment. For traders building systematic strategies, understanding these mechanics is foundational — resources like Investopedia's guide to smart order routing, the concept of market impact on Wikipedia, and implementation shortfall explained by Investopedia are worth absorbing properly before assuming your backtest translates to live performance.

The best signal in the world, poorly executed, is just a donation to whoever's on the other side of your trade.

This content is for educational purposes only and does not constitute financial product advice. Past performance is not indicative of future results. Profit Logic Ltd (ACN 688 669 936) accepts no responsibility for errors or omissions in this content or anywhere on this website. Always seek advice from a licensed financial adviser before making investment decisions.