Arcus (@arcus_xyz): How Arcus Handles Equity Perps Outside Regular Trading Hours

How Arcus Handles Equity Perps Outside Regular Trading Hours An Equity Perpetual on Arcus tracks an equity's price, but it isn't bound to the equity's exchange hours. The contract lives on Arcus, not on the NYSE, so it trades continuously, including the hours when the underlying market is shut. You can open, close, or adjust a position at 2 a.m. on a Sunday the same way you would at 11 a.m. on a Tuesday. That continuity is the point of the instrument. News doesn't wait for the opening bell, and neither do equity perpetuals. But trading an equity's price while the equity itself isn't trading creates a problem the venue has to solve. The Problem Off Hours Trading Has to Solve While the underlying is open, a deep, live market prices the equity every second, and the perp has something solid to track. When the market closes, that anchor disappears. There's no fresh reference price, volume thins out, and a single outsized order can push the perp further than any real information would justify. On a careless venue, that's how a quiet weekend becomes a liquidation cascade: a thin book, a stray print, and a wave of forced closes that had nothing to do with news. Three mechanisms on Arcus are designed to prevent it. What Changes When the Underlying Closes Opening a new position takes more margin:The initial margin requirement rises off-hours, currently by 50%, across non-crypto markets. With less liquidity to absorb a move, putting on fresh risk costs more, which discourages overexposure in exactly the conditions where it's most dangerous, and makes it costlier for anyone trying to move a thin market deliberately. Price moves are held within bands:Trades can't execute outside a range set around the last regular-hours settlement price, a VWAP sealed at the close: ±0.5× the initial margin ratio on either side. If the book pushes persistently against a bound for over an hour, the band expands in steps (1×, then 2×, then 4× of initial margin) and only in the direction of that pressure. A real earnings surprise or a geopolitical shock still gets through. A one-off print doesn't. Funding holds at a fixed rate:During regular hours, funding combines a premium component (perp vs. underlying) with a base rate. Outside regular hours, there's no reliable external price to measure the premium against, so the premium is dropped and funding snaps to the base rate until the market reopens. Underneath all three, the mark price changes character too. During regular hours it's anchored to the oracle. Outside regular hours, it becomes a 2.5-minute exponentially weighted moving average of the perp's own impact mid price, bounded by the price bands and smoothed by design, so liquidations don't trigger on a single stray trade. What it Means for a Position You Already Hold The margin change applies only to opening new positions. Maintenance margin does not rise off-hours, which means a position you already hold isn't suddenly closer to liquidation because the market closed. Its liquidation price doesn't move when the bell rings on Friday. The guardrails make it harder to take on fresh risk in thin conditions, without penalizing the risk you were already carrying Which Markets This Applies To The off-hours regime follows the underlying asset's trading hours. It applies to single stocks, commodity ETFs, and index ETFs, where US regular hours typically run 04:00–20:00 ET (pre through post-market); the exact calendar is per-market. Crypto perps have no off-hours regime at all, because crypto never closes. TL;DR An Equity Perpetual keeps trading when the stock market closes. Three things adjust while the underlying is shut: initial margin rises by 50%, price moves are held within bands that widen only under sustained pressure, and funding holds at a base rate (SOFR + 0.5%). Maintenance margin doesn't change, so open positions aren't pushed closer to liquidation. Real news still moves the market; a quiet weekend isn’t likely to cascade into forced closes. Spot trading is live at app.arcus.xyz. Equity Perpetuals are live in beta, gated by waitlist. Join at waitlist.arcus.xyz. ➢ https://arcus.xyz/blog/how-arcus-handles-equity-perps-outside-regular-trading-hours