// THE MECHANISM
How a stop price is worked out, and where it is kept
A stop is simple arithmetic on a price you already know. What matters is which price it is measured from, when it moves, and who is watching for it.
Two reference points: the fill and the high
A fixed stop-loss uses the price your buy filled at. Multiply that price by one minus your percentage and you have the stop. It is set once, at the fill, and it does not react to anything the market does next.
A trailing stop uses a second number: the highest price seen since the fill. On the first update the high is the fill itself, so a 5% trail starts 5% below the fill. After that the high can only rise. A trailing stop that followed the price back down would never be reached, so it is never allowed to.
A worked example: watching the stop price move
Say a paper buy fills at 100. You set Stop Loss % Below Fill to 8 and Trailing Stop % to 5. The fixed stop is 92. The trailing stop starts at 95. The higher price applies, so the stop in force is 95.
The price climbs to 110, and the trailing stop rises to 104.50. It reaches 120, and the stop moves to 114. Then the price slips back to 116. The high is still 120, so the stop stays at 114. If a later update prints 113.80, that is at or below the stop, and Vectixs sends a market sell at that price.
Held by Vectixs, not by the exchange
None of the four exchanges here receives a stop order from Vectixs. Vectixs keeps the stop itself. It checks every price update for that pair, and when the price touches the stop it sells at market. That has two plain consequences, and the order form states both.
First, a market sell takes the price that is there. If the price gaps through the stop between updates, the sale fills below the stop price. Second, nothing fires while Vectixs is offline. The high since the fill is saved at most every 30 seconds, so after a restart the trail can sit slightly lower than where it had climbed.
Choosing a trail width without guessing
Width is a trade-off between two failure modes. A tight trail sits close to the price, so an ordinary swing can reach it and close a position that was only wobbling. A wide trail rides out more noise, but the price has to fall further from its high before the stop is touched.
No width suits every pair. A coin that routinely swings several percent in an hour behaves differently from one that drifts. Paper is a cheap place to compare: place a few small buys on the same pair with different trails, then read in Recent Trades which ones closed, and when.