> For the complete documentation index, see [llms.txt](https://docs.contango.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.contango.xyz/basics/how-does-it-work.md). # How does it work? Contango builds positions by automating [looping](/basics/what-is-looping.md) strategies, through [flash loans](/resources/glossary.md#flash-loan). When a trader opens a long ETH/DAI position with DAI as margin, the protocol gets the remaining DAI from a flash loan, swaps all DAI for ETH on the spot market, and lends ETH on a money market, to borrow DAI and repay the flash loan.

High level explanation of how Contango synthetizes a long ETH/DAI position

When closing a position, Contango simply undoes the above steps. Please note that currently Contango has integrated with [*variable-rate* markets](/resources/glossary.md#money-market) (which does not necessarily close the door to integrations with *fixed-rate* markets too). Below is a detailed explanation how Contango builds long and short positions. The following sub-section examines in detail a [real transaction](/basics/how-does-it-work/detailed-tx-analysis.md). ### Long position #### Quote currency as margin If a trader wants to long ETH with some DAI as margin, Contango will first obtain the remaining DAI with a flash loan, swap all DAI for ETH, lend that ETH on a variable rate market, and borrow DAI against it to reimburses the initial flash loan. The diagram below recaps these steps and provides a numerical example when a trader longs 1 ETH with 200 DAI as margin, and spot ETH = 1000 DAI.

Steps carried out to open a long ETH/DAI position, with DAI as margin

#### Base currency as margin If a trader wants to long ETH with some ETH as margin, Contango will first obtain DAI with a flash loan, swap DAI for ETH, lend that ETH + the ETH posted as margin, and borrow DAI against it to reimburses the initial flash loan. The diagram below recaps these steps and provides a numerical example when a trader longs 1 ETH with 0.2 ETH as margin, and spot ETH = 1000 DAI.

Steps carried out to open a long ETH/DAI position, with ETH as margin

### Short position Short are built slightly different from the above flow. * Effectively, shorts are longs on the inverse contract with a +1 on the leverage. For instance, a 2x ETH/DAI short is like a 3x long on the inverse DAI/ETH contract. This is because you need the full notional exposure on the asset you're shorting for your PnL to be coherent. * A consequence of this is that you always have a liquidation price on Contango, even at 1x leverage. #### Quote currency as margin If a trader wants to short ETH with some DAI as margin, Contango will first obtain the full ETH exposure with a flash loan, swap all ETH for DAI, lend that DAI on a variable rate market, and borrow ETH against it to reimburses the initial flash loan. The diagram below recaps these steps and provides a numerical example when a trader shorts 1 ETH with 200 DAI as margin, and spot ETH = 1000 DAI.

Steps carried out to open a short ETH/DAI position, with DAI as margin

#### Base currency as margin If a trader wants to short ETH with some ETH as margin, Contango will first obtain the full ETH exposure with a flash loan, swap all ETH for DAI, lend that DAI on a variable rate market, and borrow ETH against it to reimburses the initial flash loan. The diagram below recaps these steps and provides a numerical example when a trader shorts 1 ETH with 0.2 ETH as margin, and spot ETH = 1000 DAI.