Short Sale Volume

What share of the S&P 500's daily trading volume is flagged as a short sale, from FINRA's free daily Reg SHO files. It is a free proxy for short-selling activity, since short interest data is now behind FINRA's paid API Console.
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Market Median SVR
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Short volume ÷ total volume
Window
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Trading days covered
Most-Shorted Sector
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Median sector SVR
Least-Shorted Sector
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Median sector SVR

Median short sale volume ratio by sector

Median of each stock's trailing ~1-month average (short volume ÷ total volume), by GICS sector.

Market median short sale volume ratio over time

One point per trading day, computed directly from FINRA's daily files. The full window is filled from the first run.

Does elevated short-selling predict weaker forward returns?

Each point is one stock. X is its average short-sale-volume ratio over the older half of the window, Y is its relative return vs. SPY over the newer half. The two periods don't overlap.

Most Shorted

Highest average short-sale-volume ratio, trailing ~1 month
SymbolSectorSVR
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Least Shorted

Lowest average short-sale-volume ratio, trailing ~1 month
SymbolSectorSVR
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Full S&P 500

Trailing ~1-month average short-sale-volume ratio per constituent
Show full list
Symbol Sector Avg. SVR▾ Rank▾
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Methodology

Data. The universe is the S&P 500. The data is FINRA's daily Regulation SHO short-sale-volume file (the "CNMS" tape), published free at a per-date URL with no registration. FINRA's short interest data (total shares held short, reported twice a month) is behind a paid, registration-gated API Console, so it isn't used. Short sale volume and short interest are different metrics. This page measures a flow: the share of a stock's daily volume executed as a short sale. It doesn't measure a stock of outstanding short positions. A high short-sale-volume ratio (SVR) doesn't necessarily mean a large short position is building, since some of that volume closes out the same day or is market-maker hedging. It's an imperfect proxy for short-selling activity, not a substitute for short interest.

Calculation. For each company, SVR on a given day is ShortVolume / TotalVolume from that day's FINRA file. The sector chart, leaderboards and full table use each stock's average SVR over the most recent ~21 trading days. The market-median trend chart plots the market-wide median SVR for every trading day in FINRA's files. FINRA republishes full daily history, so the whole ~3-month window is built in a single run.

Forward-return test. It splits the ~3-month window into two non-overlapping halves, the same overlapping-window issue covered on Share Count Trends and Relative Strength Leaders/Laggards. Each stock's average SVR over the older half is the predictor, and its return relative to SPY over the newer half (Yahoo Finance daily adjusted closes) is the outcome. A negative relationship would match the finding that short sellers are informed (e.g. Diether, Lee & Werner, 2009): more short-sale activity before weaker returns. A flat or positive one would mean it isn't showing up in this window. Pearson (linear) and Spearman (rank) fits are both shown, as on Factor Analysis.

Company name and sector come from Sector Beeswarm. Dual-share-class tickers (e.g. Berkshire Hathaway's B shares) use a dash in the site's ticker convention and a dot in FINRA's data. Both forms are tried, and a ticker is left out if neither matches. This is a one-time snapshot for now. Refresh manually for a newer window.