You may experience cases where a Contract Option is not enabled for short-selling. In such cases, you will receive the following error message: "You are selling contracts you do not own or trying to close more than you currently hold. Check you are trading from the correct sub-account and have no existing orders to sell the instrument."
This issue is connected to the rating of the Contract Option. If the rating of a Contract Option is 6, then it is not possible to short-sell it under any circumstances, even as part of covered call. You will always be able to find the rating of an instrument in the Trading Conditions under Instrument.
The rating is determined by Saxo with rating 6 being the lowest rating possible (lowest in this context means most risky). A significant part of the rating depends on the market capitalization, liquidity, volatility, country of incorporation, industry and M&A Activity of the underlying instrument.