The price you watch, the price that triggers your stop and the price you receive can be different. Before explaining why a stop did or did not activate, identify which price stream its condition actually watches.
This Read the Reaction lesson uses Bybit’s documented derivatives choices as one venue-specific example. It does not assume every exchange, spot market or order type offers the same options. Our previous liquidity lesson examined the cost of matching an order; here we examine what activates it.
Three prices describe different things
- Last traded price: the latest completed trade in the particular contract market. A last-price candle summarizes those trades, not every other reference price.
- Index price: a calculated reference built from component markets. Bybit’s index methodology generally uses weighted spot inputs, with special rules and fallbacks. It is not a standing offer to trade at the index value.
- Mark price: a calculated contract reference used for valuation and risk. Bybit’s mark methodology incorporates index and basis inputs, reflecting the relationship between contract and spot prices; the exact calculation varies by product and circumstances. Mark is not simply another name for last or index.
The distinction matters around news, when local trades and reference inputs can change differently. None of these prices explains participants’ intentions or proves that a headline caused the move.
Read the saved order, not just the chart
Bybit’s derivatives order reference supports last, mark and index trigger sources. Its take-profit/stop-loss (TP/SL) guide also distinguishes the reference price from whether activation produces a market or limit order.
Check the saved order’s source, threshold, direction and execution type. Separately check the chart’s symbol and price series. A last-price wick touching 99 does not demonstrate that mark reached 99. A closing-price trading rule also differs from a stop evaluated as prices update; do not assume it waits for a candle close.
One threshold, three activation times
Imagine a fictional USDT-quoted perpetual contract. Compare three independent versions of the same long-position sell stop, one per reference source. Each is already accepted and waiting at T0, with this teaching rule:
Activate on the first update where the selected reference price is less than or equal to 99.00 USDT per underlying unit.
Equality counts. Assume the table contains every reference update during this short exercise, with values held between rows, no earlier crossing and no additional trigger-protection condition. These are invented prices, not a reconstruction of Bybit’s mark formula or an observed news event. The three stops are alternatives, not three orders sharing one position. Each position remains eligible until its own trigger, without intervening liquidation or cancellation.
| Time | Last | Mark | Index |
|---|---|---|---|
| T0 | 100.00 | 100.00 | 100.00 |
| T1 | 98.80 | 99.30 | 99.40 |
| T2 | 99.20 | 98.90 | 99.10 |
| T3 | 98.70 | 98.80 | 99.00 |
The last-based stop activates at T1: 98.80 < 99.00. Mark and index are still above the boundary. The mark-based version activates at T2: 98.90 < 99.00, even though last has recovered to 99.20. The index-based version activates at T3: 99.00 = 99.00.
Last’s recovery at T2 does not undo its earlier activation. Nor does this sequence establish a universal ordering: another sequence could put mark first. The result only identifies the first qualifying update under each specified rule, not which choice produces a better trade.
Activation is not the fill price
Suppose the last-based stop releases a market sell at T1 and its eventual average fill is 98.60. That additional fill is hypothetical, not calculated from the table. It is 0.40 USDT per unit below the 99.00 threshold and 0.20 below the 98.80 triggering observation, before fees. Triggering did not reserve a buyer at 99.00.
Changing the released order to a sell limit at 98.90 changes the execution constraint. If all available bids are below 98.90 when it arrives, it cannot immediately match. Its later fate depends on prices, quantity and time-in-force—the instruction controlling how long an unfilled order remains active. A triggered stop-limit can leave exposure open.
Bybit documents execution protections and possible non-execution for market orders too. Avoid interpreting “market” as an unconditional guarantee of a complete exit. Our risk and position-sizing guide explains why a planned stop distance is not a guaranteed maximum loss.
Check protection rules and margin separately
Bybit’s TP/SL Price Protection can delay eligible last-price TP/SL triggers when last and mark diverge beyond a configured threshold. Its documentation excludes mark/index triggers and API-submitted orders from that feature. Do not confuse this activation check with protection applied during order matching. Our table deliberately excludes an extra activation gate.
Liquidation is another process. Under Bybit’s isolated-margin rules, mark reaching the position’s liquidation price triggers liquidation. A last-price chart alone cannot establish whether that happened. Choosing mark for a stop does not guarantee an exit before liquidation; account conditions and execution still matter. Check the applicable margin mode rather than borrowing a liquidation rule from another account type.
Keep a record you can reconcile
Before relying on a stop, save the contract, side, quantity, reference source, threshold, execution type and any protection settings. Afterward, distinguish the trigger timestamp, resulting order status and actual fills. Use the correct reference history around that timestamp, not just the latest candle screenshot.
If the evidence is incomplete, record what is missing instead of labeling the event a malfunction or manipulation. A source mismatch, an unfilled limit and a canceled order are different explanations that require different records.
Educational only, not financial advice. This example measures trigger logic, not strategy performance; no reference source removes execution or liquidation risk.
