Market, limit, stop: the order type is part of the trade

Every trade carries two risks that cannot both be eliminated: the risk of not transacting, and the risk of transacting at a bad price. Order types are the mechanism for choosing which one you accept.

The core three

1. Market order: executes immediately against the best available prices. Certain completion, uncertain price.
2. Limit order: executes only at your price or better. Certain price, uncertain completion.
3. Stop order: dormant until a trigger price trades, then becomes a market order — with all the price uncertainty that implies.

Where it goes wrong

Stop orders are the common trap. In a fast, thin market the trigger and the fill can be far apart, because there may be no resting bids near the stop level. A stop-limit order caps that damage but reintroduces the risk of no fill at all, which is precisely the outcome a protective stop was meant to prevent.

Auctions and after-hours

Opening and closing auctions concentrate liquidity into a single price and are often the cheapest moments to trade size. Outside regular hours, depth thins dramatically; an order that behaves predictably at midday can fill at a startling level at seven in the morning.