Amer Plunges 4.62% on Sector-Wide Pullback as 3.3B in Volume Lands It 384th Most Traded

On October 10, 2025, Amer (AS) closed at a 4.62% decline with $0.33 billion in trading volume, ranking 384th in market activity for the day. The selloff occurred amid mixed sectoral performances and evolving macroeconomic expectations.

Analysts noted the decline reflected broader investor caution toward consumer discretionary stocks following recent earnings releases. While no material company-specific news emerged, the stock's performance aligned with a sector-wide pullback triggered by revised Q4 guidance from key retail peers. Technical indicators showed heavy short-term pressure as momentum indicators crossed critical thresholds.

To build a robust back-test I’ll need to pin down a few practical details that aren’t fully specified yet: 1. Universe. Should I screen the entire U.S. stock market (e.g., all NYSE + NASDAQ common shares), or a narrower list (e.g., Russell 3000 constituents, S&P 500, etc.)? 2. Trade timing & price. Execute the buy at today’s close and liquidate at tomorrow’s close (close-to-close), or open-to-close, or open-to-open? 3. Weighting. Equal-weight each of the 500 names, or dollar-weight by volume, market cap, etc.? 4. Rebalance frequency. Re-rank every trading day (i.e., form a new top-500 list each day), correct? Once these are confirmed I can generate the trade signals and run the portfolio-level back-test from 2022-01-03 through 2025-10-10.