Список проголосовавших за комментарий "Поверхностное гугление:<br/> <blockquote>I found out why. In case anybody else has the same problem: IBKR has this «Limited Options» trading permission where they allow non naked options positions. My account was set to that automatically when only US options are chosen. They have the checkbox for «limited options» but it can't be unchecked to allow unlimited options unless all markets options trading permission is checked. That's what I did.</blockquote>(<a href="/r.php?u=https%3A%2F%2Fwww.reddit.com%2Fr%2Foptions%2Fcomments%2F85gcwp%2Fopening_a_short_callput_position_in_interactive%2F&s=485185373">https://www.reddit.com/r/options/comments/85gcwp/opening_a_short_callput_position_in_interactive/</a>)<br/> <br/> Т.е. по умолчанию разрешен шорт только US опционов, нужно где-то галочку поставить."