Gap risk: when the stop can't save you

After this lesson you'll know the one situation where a stop cannot hold your loss to 1R, and what your real defenses are.

What a stop really promises

A stop is an instruction: once the stock trades at my level, sell my shares at the market. It decides when you sell. The price you get is whatever buyers are offering at that moment. During a normal session in a liquid stock the difference is cents, and a 1R loss landing as a 1.05R loss is the ordinary cost of doing business.

The exception is the gap. Markets close at night and on weekends. Companies go on releasing news in those hours, and much of it arrives then by design. A company reports earnings an hour after the US close and the results are bad. Overnight, in the thin after-hours and pre-market sessions, the price finds its new level, and the next morning the stock simply opens there. Every price between yesterday's close and today's open never traded. Your stop was somewhere in that untraded zone. It triggers on the open, and you sell at the open's price.

The arithmetic

200 shares, entry €40, stop €38, so R = €400. The company warns on profits overnight and the stock opens at €29.

Your stop fires on the open and fills near €29. The loss is 200 × €11 = €2,200, which is 5.5R on a trade planned for one. Nobody moved a stop or broke a rule here. The loss reached 5.5R because the market was closed when the news arrived, and no order type can trade through a closed market.

How often, and when

Most nights nothing happens; the typical overnight move in a large liquid stock is well under a percent. The big gaps cluster around events you can see coming, and earnings dominate that list. Reporting dates are published weeks in advance. Drug companies add scheduled regulatory decisions. Beyond the calendar sits the genuinely unforeseeable (a fraud coming to light, say), which is rarer but real. Trading halts belong in this lesson too: when big news lands mid-session, the exchange pauses the stock and it reopens wherever the auction puts it, with the same mechanics as a small gap.

The defenses

There are three, and none of them involves a cleverer order type.

1. Know your event dates. Before entering, check when the company reports. Holding a full-size position into an earnings night means accepting that tonight the stop may not hold the loss to 1R. Traders do accept that deliberately sometimes, at reduced size (School IX, course 3 discusses when). Doing it knowingly is the point.
2. Size. The gap loss scaled with the position: 5.5R hurt because the whole position gapped. This is one more reason the position cap from course 3 exists, and School VI extends the idea to the whole book — five positions all reporting in the same week turn out to be one big position.
3. Time. A trade closed before the session ends carries no overnight gap risk at all. Day-trading buys that safety at a steep price in costs (School I, course 9 put numbers on it), so it's a trade-off you pay for rather than something you get free.

Deliberately missing from the list: any order type. A stop-limit doesn't help here, and School I, course 10 shows how it makes a gap strictly worse.

One night, with real numbers

On 2 February 2022, Meta Platforms reported after the close. The stock had finished that session a little above $320. It reported a first-ever decline in daily users and guided revenue below expectations, and the next morning it opened roughly a quarter lower, closing the day down 26%. About $251 billion of market value went with it, the largest single-day loss in market history at the time. Not one share traded at any price between the Wednesday close and the Thursday open.

Now put a trader in it. Entry $330, stop $317, which is a sensible level just under the prior week's low and about 4% away. 100 shares, so R = $1,300. The stop sat at the broker as a working order all night and did precisely what a stop does: it became a market order at the open and filled near $245. The loss was about $8,500, or 6.5R. The decision that mattered had been taken weeks earlier, when the trader chose to carry a full-sized position into a date the company had published in advance.

Check yourself

1. 150 shares, entry €22, stop €21, so R = €150. The stock opens at €17.50 after an overnight profit warning. Loss in euros and in R? (150 × €4.50 = €675, which is 4.5R.)
2. Which gaps can you see coming, and where do you look? (The scheduled ones, earnings above all. The reporting date is public weeks ahead.)
3. Why can't a better order type fix gap risk? (Every price between the close and the open never traded. No instruction can execute at a price that doesn't exist.)

The habit this lesson installs

Before every entry, know the next date this company makes news on purpose.

Next: Course 7 — "The risk ritual," where the whole school assembles into one routine.