Reconciling Cash And Margin

Every trading desk keeps its own internal ledger of cash, positions and margin — but the broker or prime broker keeps an independent ledger too, built from the same trades but processed through different systems. Reconciliation is the daily (sometimes intraday) process of comparing the two and explaining every difference, however small. It sounds like pure back-office plumbing, but for a systematic desk it's an early-warning system: a fill that was booked at the wrong price, a corporate action that was applied once internally but twice by the broker, or a failed trade that never actually settled will all show up first as a reconciliation break, often before any risk report would catch it.

Most breaks are timing differences — a trade settles on the broker's side a few hours before it hits the internal ledger — and resolve themselves overnight. The breaks worth escalating immediately are ones that persist past the next business day, or ones in margin rather than cash, since a margin discrepancy on a leveraged book can mean the desk is carrying more risk than its own numbers suggest.

Concrete illustration. A fund's internal system shows $4.2m cash and 50,000 shares of a stock; the prime broker's statement shows $4.15m cash and 50,000 shares. The $50k gap traces to a dividend that was declared ex-date yesterday: the broker credited it same-day, the internal system posts dividend accruals with a one-day lag. That's a known, explainable timing break, not an error — but the reconciliation process is exactly what surfaces it and confirms it isn't something worse.