USDT-M or COIN-M on BYDFi? The real difference is what you post as margin and what you get paid in

BYDFi offers both USDT-M and COIN-M perpetuals, and its help center has a short guide on who each one suits. The leverage and order types work the same either way. The difference is the coin you post as margin and the coin your profit and loss lands in.

The image is the official banner from that BYDFi guide, a cartoon trader shrugging between a Bitcoin coin and a Tether coin with YES and NO bubbles overhead.

USDT-M perpetuals

• Quoted and settled in USDT
• You hold USDT as collateral and can go long or short with the same buying power
• PnL is in dollars, so it's easy to work out what you made or lost
• No expiry, so a position stays open until you close it or it gets liquidated

BYDFi's take: this suits traders who move in and out quickly on specific setups, and people who want to stay in stablecoins during long declines.

COIN-M perpetuals

• Settled in the underlying coin, for example ETH for the ETH COIN-M contract
• You fund margin with the coin you already hold, no swapping to stablecoins first
• Profit is paid in that coin, so in an uptrend you gain on the trade and on the coin itself
• You can hedge a coin you hold by shorting its COIN-M contract without selling it

BYDFi's take: this fits long-term holders who want to stay in the coin.

The part the guide hints at

On COIN-M your margin is the volatile asset itself. When price falls, your collateral shrinks along with any long PnL, which is why the guide tells holders to be careful with it. A short on COIN-M against coins you hold works more like a hedge, since the loss on the position and the gain on the margin move against each other.

Quick way to pick

• You think in dollars and trade short-term: USDT-M
• You hold the coin long-term and want to keep stacking it or hedge it without selling: COIN-M
• You're not sure: start with USDT-M, since the PnL is easier to read

The guide's closing point: it depends on your experience and how much risk you can take, not on which one sounds more advanced.