# Are stop losses triggered by trade price or bid price?

**URL:** <https://forum.alpaca.markets/t/are-stop-losses-triggered-by-trade-price-or-bid-price/5021>\
**Category:** Alpaca Trading\
**Created:** [March 18, 2021, 3:04pm UTC](https://forum.alpaca.markets/t/are-stop-losses-triggered-by-trade-price-or-bid-price/5021 "2021-03-18T15:04:13Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![msieg](https://avatars.discourse-cdn.com/v4/letter/m/e9a140/32.png) [@msieg](https://forum.alpaca.markets/u/msieg)\
**Post date:** [March 18, 2021, 3:04pm UTC](https://forum.alpaca.markets/t/are-stop-losses-triggered-by-trade-price-or-bid-price/5021/1 "2021-03-18T15:04:13Z")

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This seems like an important distinction. If the bid price suddenly dips below my stop loss, but nobody sells to that bidder, does the stop loss get triggered?

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**Author:** ![Dan\_Whitnable\_Alpaca](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.alpaca.markets/dan_whitnable_alpaca/32/1658_2.png) [@Dan\_Whitnable\_Alpaca](https://forum.alpaca.markets/u/Dan_Whitnable_Alpaca)\
**Post date:** [March 18, 2021, 3:21pm UTC](https://forum.alpaca.markets/t/are-stop-losses-triggered-by-trade-price-or-bid-price/5021/2 "2021-03-18T15:21:55Z")

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Stop orders are triggered by the last ‘valid’ trade price. What is a ‘valid’ trade? Here is the list of conditions which exclude a trade from being valid.

| Feed | Tape | Condition | Description |
| --- | --- | --- | --- |
| CTS | AB | B | Average Price Trade |
| UTDF | C | W | Average Price Trade |
| CTS/UTDF | ABC | 4 | Derivatively Priced |
| CTS/UTDF | ABC | 7 | Qualified Contingent Trade (“QCT”) |
| CTS/UTDF | ABC | 9 | Corrected Consolidated Close (per listing market) |
| CTS/UTDF | ABC | C | Cash Sale |
| CTS/UTDF | ABC | G | Bunched Sold Trade |
| CTS/UTDF | ABC | H | Price Variation Trade |
| CTS/UTDF | ABC | I | Odd Lot Trade |
| CTS/UTDF | ABC | N | Next Day |
| CTS/UTDF | ABC | P | Prior Reference Price |
| CTS/UTDF | ABC | Q | Market Center Official Open |
| CTS/UTDF | ABC | R | Seller |
| CTS/UTDF | ABC | T | Form T |
| CTS/UTDF | ABC | U | Extended Trading Hours (Sold Out of Sequence) |
| CTS/UTDF | ABC | V | Contingent Trade |
| CTS/UTDF | ABC | Z | Sold (out of Sequence) |

Those are ‘condition’ parameters set for each trade which appears on the SIP data feeds. If a trade has one of those conditions it doesn’t trigger a stop. Additionally, the ‘market’ price that is typically displayed is also not updated.

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**Author:** ![learning\_to\_trade](https://avatars.discourse-cdn.com/v4/letter/l/e9c0ed/32.png) [@learning\_to\_trade](https://forum.alpaca.markets/u/learning_to_trade)\
**Post date:** [March 18, 2021, 8:40pm UTC](https://forum.alpaca.markets/t/are-stop-losses-triggered-by-trade-price-or-bid-price/5021/3 "2021-03-18T20:40:39Z")

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Thank you for this explanation