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  • Writer's pictureRakshith B B

Decoding Prop Firms' Business Models: A-Book vs. B-Book

In the dynamic world of proprietary (prop) trading, understanding the intricacies of how firms operate can be the key to navigating the market effectively. One of the most pivotal distinctions lies between the A-Book and B-Book business models of prop firms. But what exactly sets these two models apart? And, more crucially, how do they impact traders and the profitability of the firms themselves?

A-Book Prop Firms: Partnering in Profits

At the heart of the A-Book model is a symbiotic relationship between the trader and the firm. Simply put, when a trader profits, so does the A-Book prop firm. This alignment of interests often creates an environment where traders feel that the firm is rooting for their success. After all, a trader's win translates to the firm's gain.

But where does the revenue come from? Primarily, it arises from two sources:

1. Evaluation Fee: Before traders are allowed to handle significant capital, they undergo an evaluation phase. This assessment often comes with a fee, which contributes to the firm's revenue.

2. Investor Capital: Beyond the evaluation fee, the primary source of revenue is the capital that investors entrust the firm with. As traders generate returns on this capital, the firm earns its share.

B-Book Prop Firms: Profiting from Pitfalls

Contrastingly, B-Book prop firms operate on a different premise. Their profit is inversely proportional to the trader's success. If a trader incurs losses, the B-Book prop firm stands to gain. This model might raise eyebrows due to potential conflicts of interest. However, it's essential to understand that the firm's primary revenue in this model is not from the trader's losses but from the evaluation fee. Given that only a minuscule percentage of traders make it through the evaluation phase, this fee becomes a significant and steady revenue stream for B-Book prop firms.

A Win-Win Scenario?

Despite the contrasting ways in which they earn revenue, both models can be highly profitable for prop firms. The evaluation fees provide a consistent inflow, especially considering the high attrition rate of traders during evaluations. On the A-Book side, the dual revenue from both evaluation fees and investor capital ensures a healthy bottom line, while the B-Book model leans heavily on the evaluation fees.

For traders, understanding these models is crucial. Knowledge of how a firm profits can offer insights into its operational ethos and alignment with trader success.


The prop trading world is complex and multifaceted. Whether you're a budding trader or an investor looking to dive into this space, understanding the nuances of A-Book and B-Book models is vital. Armed with this knowledge, you can make informed decisions, aligning with firms that best match your trading objectives and ethos.

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