Order mechanics
A Stop Order Is Not a Guarantee
A stop is an instruction to exit at a level, not a promise of a price. Why fills land past the level, and what a guaranteed stop actually costs.
4 min read
The archive
All articles
What has been measured about how traders decide, what a mistake is allowed to cost, and which of this field's favourite numbers survive being traced — newest first.
12 articles
The quoted costs
Bid, Ask, and the Space Between Them
Every quoted market runs two prices at once: one you can sell into, one you can buy from. What each is, and why there are never fewer than two.
4 min read
The quoted costs
Commission Models: Per-Lot, Per-Side, Spread-Only
Zero-commission is not zero-cost. How the three charging models work, why they are not comparable on either number alone, and how to add both halves up.
4 min read
Execution and liquidity
How Trading Costs Change With Your Style
The same cost base is trivial for one trader and decisive for another. Which components dominate for scalpers, day traders, swing traders and position holders.
4 min read
Execution and liquidity
Liquidity, and Why the Same Order Costs More at 2am
Liquidity is how much can trade near the current price without moving it. What thin books do to your fill, and why the hour matters more than the instrument.
4 min read
Order mechanics
Order Types: What Each Promises, What Each Costs
Market, limit and stop orders are three positions on one trade-off: certainty of execution against certainty of price. What each really guarantees.
4 min read
The quoted costs
Overnight Financing: What You Pay to Hold
A daily charge for holding a leveraged position past the cut-off. Why it exists, how it compounds, and why it decides whether a long hold was worth it.
4 min read
The unquoted costs
Slippage: Why the Fill Isn't the Price
The difference between the price you asked for and the price you got. What causes it, why it is not a broker trick, and what you can control.
4 min read
The unquoted costs
The Costs Nobody Quotes You
Inactivity fees, withdrawal charges, currency conversion and data subscriptions. All disclosed somewhere, almost never on the page selling you the spread.
4 min read
The quoted costs
What a Spread Is, and Who Decides It
The spread is the gap between the buy and sell price, and it is the first cost of every trade. What it is, who sets it, and why it changes during the day.
6 min read
The quoted costs
What Trading Costs Actually Consist Of
Trading costs are not one number. They are a stack of charges and frictions, set by different people, arriving at different moments. Here is the stack.
4 min read
The unquoted costs
When Spreads Widen — and Why It's Predictable
The advertised spread is observed under good conditions. Here is when conditions are not good — releases, session edges, rollover — and why it is foreseeable.
4 min read