When Yesterday's P\&L Gets Restated

Even "final" P&L, reconciled and published at the end of the day, isn't always the last word. A trade booked incorrectly can be caught and corrected days later, a broker's confirmed price can be amended after their own reconciliation, or a corporate action can be applied retroactively once its exact terms are confirmed. When any of these happens, the P&L for a day that already closed gets restated — the historical number changes, sometimes materially, after the fact.

Restatements are normal in small numbers, but they need discipline: every restatement should be traceable to a specific cause, approved by someone other than the trader whose P&L is changing, and clearly flagged wherever historical P&L is displayed so nobody mistakes an old, now-superseded number for the current truth. Left undisciplined, frequent unexplained restatements erode trust in every number the desk reports, including the ones that were actually correct the first time.

Worked example

A trade booked three weeks ago at the wrong price is discovered during a routine broker reconciliation. Correcting it moves that day's P&L from a reported +$22,000 down to +$9,000 — a $13,000 restatement. Operations documents the cause (a mis-keyed price), gets sign-off from a risk manager uninvolved in the original trade, and updates the historical P&L record with a visible note explaining the change, so anyone pulling that day's number later sees both the correction and its reason.