> For the complete documentation index, see [llms.txt](https://eako-capital.gitbook.io/eako-user-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://eako-capital.gitbook.io/eako-user-guide/variations-on-barrier-options/european-knock-out.md).

# European Knock-Out

A European Knock-Out is a Vanilla option where the Knock-Out barrier only exists on the expiry date at expiry time, i.e., the option ceases to exist if:

* for "up & out" barriers: The spot rate ends above the KO level
* for "down & out" barriers: The spot rate ends below the KO level

It must be noticed that a European Knock-Out is also a European Knock-In: an "up & out" is equivalent to a "down & in" and a "down & out" is equivalent to an "up & in".


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