# What is A-book?

> A-book describes trades the firm passes to a real market or liquidity provider; in prop firms, it usually means mirroring selected traders' positions with live capital.

- Source: https://pipvalley.com/glossary/a-book
- Publisher: PipValley - web design studio for prop trading firms
- Updated: 2026-10-03

In a prop firm, A-booking means taking a trader's positions, usually from the simulated funded account, and replicating them on a live account with a broker or liquidity provider. The firm's real profit or loss then follows the trader's results, which can offset the performance rewards it pays.

Firms rarely A-book everyone. It costs money (spreads, commissions, platform and bridge fees) and only makes sense for traders with a record of consistent results. Firms that do it typically set criteria and keep the decision internal.

A-booking the firm's own capital does not by itself make the trader's account live; the trader still trades the simulated account unless the firm says otherwise.

## Why it matters

A-book capacity changes how much payout liability you can carry for your best traders and is a common reason firms build broker relationships. If you do it and want to talk about it publicly, describe it accurately: what is mirrored, when, and that the trader's own account remains simulated unless stated otherwise.