You can open a margin position by selecting “Margin" in the Order Form box and placing your desired order. Selecting “Advanced Funding Options” (3 vertical white dots) in the Order Form box provides quick access to funding parameters. If you have not manually reserved funding, Bitfinex will automatically acquire funding for you at the prevailing rate currently available. Alternatively, you can manually reserve funding via the Funding tab at any time and use it when you decide to open a margin position.
In an effort to dissuade manipulative funding behavior and ensure fair platform use for all, Bitfinex will charge one full day’s interest to the borrower on any funding that is borrowed and subsequently returned without being used in a financed position.
Read more about funding a margin position.