The stock market

Screening Filters

1. PriceBelowMA20

   • Purpose: Find stocks trading below their 20-day moving average.
   • Rationale: When broad market weakness is being investigated, names trading below a short-term trend gauge often reflect near-term selling pressure. This helps surface stocks that are currently under momentum stress and may be contributing to or reflecting the sell-off.

2. price_change_pct max 0

   • Purpose: Restrict results to stocks that are flat or down on the day.
   • Rationale: Since the user is asking about a sell-off today, this filter focuses on securities that are actually declining rather than those holding up. It helps identify the stocks most directly involved in the move lower.

3. Region = US

   • Purpose: Limit the search to U.S. stocks.
   • Rationale: The question is about “the stock market” in a U.S. context, so this keeps the screen relevant to domestic equities and avoids unrelated international names.

4. Index component = GSPC, NDX, DJI

   • Purpose: Focus on stocks in the S&P 500, Nasdaq 100, and Dow Jones Industrial Average.
   • Rationale: Sell-offs in major indexes are usually driven by large, widely followed constituents. Restricting to these index components helps identify the stocks most likely to have influenced the broader market move today.

5. news_driver = Negative

   • Purpose: Surface stocks with negative news catalysts.
   • Rationale: Market sell-offs are often driven by company-specific headlines such as earnings misses, guidance cuts, regulatory issues, lawsuits, downgrades, or macro-sensitive warnings. This filter is especially useful for explaining why a stock may have been under pressure.

6. volume < monthly_average_dollar_volume

   • Purpose: Find names trading on below-normal dollar volume.
   • Rationale: Lower-than-usual trading activity can indicate that the move is not broad participation from buyers, which may make downside moves easier to sustain. It can also help distinguish stocks that are slipping on weak demand rather than on heavy accumulation.

7. option_sentiments = Bearish

   • Purpose: Identify stocks with bearish options positioning or sentiment.
   • Rationale: Bearish options activity can reflect traders expecting further downside, often after negative news or deteriorating outlooks. This adds another layer of evidence that the stock is being viewed negatively by the market.

Why Results Match:

• The screen is designed to uncover U.S. large-cap stocks that are actually down today, which is directly relevant to understanding a market sell-off.
• By requiring negative news drivers and bearish options sentiment, it increases the chance of finding stocks with identifiable downside catalysts rather than random decliners.
• Limiting results to major index components makes the output more useful for answering what likely caused a broad market sell-off, since these names tend to have the biggest impact on the indices.
• The below-20-day moving average and negative daily price change filters highlight stocks showing near-term weakness, helping isolate the securities most aligned with the sell-off.
• The volume comparison adds context around the strength of the move, while bearish options sentiment helps confirm negative market expectations.

In short, these filters are appropriate because they target large, U.S. index-listed stocks with current downside moves, negative catalysts, and bearish trader sentiment—all of which are useful clues when trying to explain what likely caused a sell-off today.