How to tell if a broker is routing you to a B-book

[Fairman]

How to tell if a broker is routing you to a B-book

Direct proof is hard, since brokers do not publish routing. Circumstantial signs pile up though, and scalpers are often the first to notice because short-term traders are exactly who gets filtered.

Watch for these patterns. Fills are consistently identical to the quote on losers but delayed on winners. Account restrictions appear after a profitable stretch, such as widened spreads or forced minimum holding times. Prices on the platform differ from other feeds by tiny but consistent amounts, in the broker's favor. Support gets evasive about "liquidity partners".

Another clue is how the platform behaves in extreme moves. Genuine pass-through accounts show stop-outs and slippage that mirror the market. Internalized flow often looks smoother than reality, with fewer gaps than the real market had.

None of these alone proves anything. Together they paint a picture. And B-book is not automatically evil, since many reputable firms internalize some flow. The concern arises when the broker profits directly from client losses and has a motive to restrict winners.

Has any account of yours changed behavior after a good month, and how was it explained?