Margin
Margin is collateral posted against a leveraged position — the cash or securities that keep the broker or CCP whole.
Definition
Margin refers to the cash or securities that keep the broker or CCP whole. Keep that definition fixed when comparing series, managers, or regimes — renaming the same tape does not create a new signal.
Why it matters
Funding and market liquidity decide whether a position can be entered, held, or exited at size. When the cash or securities that keep the broker or CCP whole shifts, related hedges, limits, and narratives usually need an explicit update rather than a quiet assumption.
Case
Suppose a desk is positioned for the opposite of what margin is saying. If the cash or securities that keep the broker or CCP whole moves against that book, the first question is not “is the story clever?” but whether size, hedges, and stop logic still match the observation.
How to read it
Watch spreads, depth, and dealer balance-sheet proxies; headline prices can look fine while exit is gone. Prefer a short written null hypothesis for Margin: what would falsify the current reading in the next window?