Affirm Surges 2.05 on BNPL Expansion and AI Upgrades as 580M Volume Places It 169th in U.S. Trading Activity

On September 12, 2025, , , ranking 169th among U.S. stocks by trading activity. The move followed a strategic focus on expanding its buy-now-pay-later (BNPL) partnerships with major retailers, which analysts suggest could drive longer-term adoption of its platform.

Recent developments highlighted Affirm’s renewed emphasis on optimizing its payment processing infrastructure to reduce merchant fees, a key differentiator in the competitive fintech sector. The company also announced plans to enhance its AI-driven risk assessment models, aiming to improve underwriting efficiency without compromising customer acquisition rates. These operational upgrades align with broader market trends favoring scalable fintech solutions.

To run this back-test accurately I need to pin down a couple of practical details: 1. Market universe • Which exchange(s) or index universe should we scan each day when ranking by volume? • Is there a preferred ticker list (e.g., all stocks in the S&P 1500, Russell 3000, NASDAQ + NYSE common shares, etc.)? 2. Position sizing and weighting • Should the 500 names be held with equal dollar weights, or some other weighting rule? • Do we rebalance every trading day (i.e., sell yesterday’s 500 at today’s open, then buy today’s new top-volume 500)? 3. Transaction costs / slippage • Should we incorporate a per-trade commission or price slippage assumption, or treat the simulation as frictionless? Once I have these specifics, I can lay out the data-gathering plan and launch the back-test.