Upstart's 42.8% Volume Spike Drives 213th Rank as Stock Slides 6.07%

On September 25, 2025, Upstart (UPST) traded with a volume of $0.57 billion, marking a 42.8% increase from the prior day’s trading volume. The stock closed with a 6.07% decline, ranking 213th in volume among listed equities that day. The move followed a combination of market dynamics and strategic developments within the fintech sector.

Recent updates highlighted Upstart’s strategic pivot toward expanding its AI-driven lending platform to include alternative credit data sources. The company announced a partnership with a major credit bureau to integrate non-traditional financial behaviors—such as utility payments and rental history—into its underwriting models. This shift aims to broaden its customer base while maintaining risk-adjusted returns. Analysts noted the move could enhance long-term margins but cautioned that near-term execution risks remain.

Separately, regulatory scrutiny in the consumer finance space added pressure. A proposed federal rule requiring enhanced transparency for AI-based lending algorithms sparked concerns among investors. While Upstart’s models are already partially compliant, the potential for higher compliance costs and operational delays weighed on sentiment. Market participants emphasized the need for clarity on implementation timelines to assess the impact.

To run this back-test accurately I’ll need a few additional details: 1. Universe • Which market should we draw the “top-500-by-volume” list from (e.g., all U.S. listed common stocks, only S&P 500 constituents, another market)? 2. Portfolio construction • Do we weight the 500 names equally each day, or weight them by something else (e.g., by dollar volume or market-cap)? 3. Transaction timing • Buy price: today’s close, or tomorrow’s open? • Sell price: next-day close, or next-day open? Once we pin these items down I can build the daily trading signals and run the back-test from 2022-01-03 (first trading day of 2022) through today.