> For the complete documentation index, see [llms.txt](https://learn.charm.fi/charm/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://learn.charm.fi/charm/previous-products/charm-options/trading-tutorials/open-a-position/notes.md).

# Notes

{% hint style="success" %}
For all markets that are **not ETH call options**, you must **approve your wallet** before you can trade. 

This only need to be done **once for each wallet.** 
{% endhint %}

For example, to trade in the ETH Puts market**,** USDC approval is needed:

<figure><img src="/files/NgIJeCJljx6pCRmfMokq" alt=""><figcaption></figcaption></figure>

To trade in the WBTC markets, WBTC approval is needed:

<figure><img src="/files/MsaRQULYK5DYKwhnSExM" alt=""><figcaption></figcaption></figure>

To trade in the WBTC markets, WBTC approval is needed:

<figure><img src="/files/kRlLkLdoMndg2LtpItPT" alt=""><figcaption></figcaption></figure>

{% hint style="info" %}
**Selling an option** is a way to get **yields**.
{% endhint %}

This is because you can sell an option without owning it, as long as you provide 100% of the underlying as collateral. Charm will charge you the net proceeds, and you will get a yield if a particular price target is met. This is described further in [our article on yields](https://medium.com/charmfinance/why-hodl-when-you-can-yiedl-643e335f29b7).

As a result, opening a position to sell an option will cost more than buying an option, but in contrast to buying an option, it is extremely unlikely you will loose all of your investment. For example:

<figure><img src="/files/Ck23OotAcJATDVQIT68n" alt=""><figcaption></figcaption></figure>

For the example above, you pay a net cost of 0.4727 ETH, after depositing 1 ETH (ie the option size) as collateral AND receive 0.5273 ETH as a contingent yield. 0.5273 ETH will be released to you if the ETH price falls between $960, and you if the price if above $960, less than 0.5273 ETH will be released to you. When the price is more than $2040 (ie 960 \* (1+111.5%)), you will get back less than 0.4727 ETH.


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