Reading Stock Market Sentiment

Market sentiment is the collective emotional state of all market participants expressed through their actual capital allocations — not their stated opinions. The critical distinction: surveys of investor sentiment measure what people say they feel; options positioning, fund flows, and volatility pricing measure what people are doing with real money. This course focuses exclusively on the latter. Sentiment indicators derived from actual financial behaviour have demonstrable predictive value for medium-term equity returns; sentiment surveys have minimal. The discipline is identifying when sentiment has reached a sufficient extreme to function as a contrarian signal, and when it is simply a coincident reflection of a trend that will continue.

1. The Put/Call Ratio: Options Market Fear and Greed

The equity put/call ratio measures the number of put options (bearish bets) traded divided by the number of call options (bullish bets) traded across US equity options markets. A ratio above 1.0 indicates more puts than calls are trading — net bearish sentiment from options market participants. A ratio below 0.7 indicates substantially more calls than puts — net bullish sentiment, sometimes reaching levels consistent with complacency.

The CBOE publishes several versions: the equity-only put/call ratio (excludes index options), the index put/call ratio, and the total put/call ratio. The equity-only ratio is most useful for gauging retail investor sentiment because equity options are disproportionately used by individual investors for directional speculation. The index put/call ratio captures institutional hedging behaviour and tends to be persistently elevated as portfolio managers hedge long equity exposure with index puts — making it less useful as a sentiment extreme indicator in isolation.

Contrarian signal generation from the equity put/call ratio: a 10-day moving average of the equity put/call ratio above 0.95–1.0 has historically been associated with above-average subsequent equity returns over 1–3 month horizons, as the excessive pessimism built into options positioning reverses. A 10-day moving average below 0.6–0.65 has been associated with below-average subsequent returns, as excessive optimism built into call volumes tends to coincide with or shortly precede market pullbacks. Use the sector-specific market cycle framework to contextualise whether sentiment extremes are cycle-consistent before acting on them contrarily.

2. The VIX: Structure, Interpretation, and Trading Implications

The CBOE Volatility Index (VIX) is one of the most widely referenced sentiment gauges in financial markets. As covered in the CBOE exchange guide, the VIX measures the 30-day implied volatility of the S&P 500 derived from a weighted portfolio of SPX options across a wide range of strike prices and two consecutive expirations. It represents the market’s collective expectation of S&P 500 volatility over the next 30 days, annualised.

The VIX has a strong mean-reverting tendency: it spikes sharply during market stress and collapses equally quickly as conditions normalise. The long-run average of the VIX has historically been approximately 19–20. Readings below 12–13 indicate unusually low fear and complacency; readings above 30 indicate significant stress; readings above 40 represent severe dislocation (the VIX reached 82 in March 2020 and 80 in October 2008). The contrarian interpretation: VIX spikes above 30–35 have historically represented buying opportunities for patient equity investors who can accept continued short-term volatility.

VIX as a position-sizing signal. Many professional traders use the VIX level as a volatility-adjusted position-sizing input: when VIX is elevated (e.g., above 25), individual stock volatility is proportionally elevated, and position sizes should be reduced to maintain constant dollar risk per trade. Our stock position size calculator implements constant-dollar-risk sizing automatically — if the stop distance widens during high-VIX environments (which it should, to account for elevated volatility), the calculator automatically reduces share count to maintain the 1% risk rule.

Term structure of VIX futures. The VIX futures curve — the relationship between current VIX and futures prices for VIX delivery in future months — provides additional sentiment information. In normal conditions, VIX futures are in contango (future months priced above the current spot VIX), reflecting the mean-reversion tendency and the carrying cost of volatility. When VIX futures enter backwardation (spot VIX above futures prices), it signals acute near-term stress that the market expects to normalise. Sustained contango in VIX futures is consistent with a complacent, low-fear environment that often precedes elevated drawdown risk.

3. Market Breadth: The Internal Health of the Market

Market breadth measures the degree of participation in a market move — how many stocks are advancing versus declining, reaching new highs versus new lows, or trading above their long-term moving averages. Breadth indicators reveal whether an apparent market rally is broad-based (healthy) or narrow (potentially unsustainable because only a small number of large-cap stocks are pulling the index higher while most stocks are declining).

Advance-Decline Line (A/D Line): Calculates the cumulative daily difference between the number of NYSE or NASDAQ stocks advancing and those declining. An A/D line that is rising alongside the index confirms broad participation — the rally is supported by most stocks. An A/D line that is declining or flattening while the index continues to make new highs represents bearish divergence: the market advance is narrowing to fewer stocks, a historically reliable warning of deteriorating internal health that often precedes index-level corrections.

Percentage of stocks above their 200-day moving average: When 70%+ of S&P 500 stocks are trading above their 200-day SMA, the broad market is in a healthy structural uptrend across most of its components. When this percentage falls below 40–50% even as the index holds near its highs, breadth divergence signals that the index is being supported by a narrow group of large-cap stocks while the median stock is already in a downtrend. From the cycle analysis perspective, this pattern is characteristic of late-cycle behaviour where defensive large-caps provide index support while cyclical and growth stocks have already turned down.

New Highs vs New Lows: The daily count of stocks making 52-week highs versus those making 52-week lows provides another breadth dimension. In a healthy uptrend, new highs substantially outnumber new lows. When new lows begin to persistently expand even as the index remains near its high, it confirms internal deterioration. A ratio of New Highs to (New Highs + New Lows) below 50% is a warning signal; sustained readings below 30% in an uptrending index have historically preceded market tops by weeks to months.

4. Fund Flows and Positioning Data

Actual capital flows into and out of equity funds — mutual funds, ETFs, and other pooled vehicles — provide a behavioural counterpart to price-based sentiment measures. The Investment Company Institute (ICI) publishes weekly mutual fund flow data; ETF flow data is available from providers including ETF.com and Bloomberg. The contrarian signal: sustained retail outflows from equity funds at market lows (exactly when retail investors are most frightened) are associated with subsequent above-average returns; sustained inflows near market highs (when retail enthusiasm peaks) are associated with below-average returns.

CFTC Commitment of Traders (COT) reports provide weekly data on the positioning of commercial hedgers, large speculators (hedge funds), and small speculators in equity index futures. Large speculator net long positioning in S&P 500 futures at historically high levels has been associated with above-average near-term drawdown risk, as the crowded long trade is vulnerable to position unwinding when sentiment shifts. Large speculator positioning at historically net-short levels has been associated with above-average subsequent returns, as the short-covering fuel for rallies accumulates.

5. When Sentiment Signals Fail

• Sentiment can remain at extremes for extended periods. A market can remain “overbought” by sentiment measures for weeks or months during strong bull markets, and can remain deeply oversold during severe bear markets. The 2021 equity market spent most of the year in a low-VIX, high-call-buying, optimistic sentiment configuration — and the index continued to rise throughout. Sentiment extremes are better at identifying when the market is vulnerable to reversal than at timing the reversal precisely.
• Structural changes reduce historical comparability. The proliferation of retail options trading through zero-commission platforms since 2020 has altered put/call ratio baselines. The historical threshold of 0.65 as an extreme low has been observed more frequently since 2020 as retail call buying has structurally increased. Historical signal thresholds require periodic recalibration.
• Sentiment measures are coincident during trend phases. In the middle of a strong uptrend, breadth is strong, VIX is low, and the put/call ratio is favourable — all confirming the trend rather than providing contrarian signals. Sentiment measures generate their most actionable contrarian signals at turning points, not during the middle of established trends. Apply them in conjunction with the market structure framework to determine when a turning point is plausible.

Key Takeaways

• Stock Position Size Calculator — reduce position sizes when VIX is elevated by widening the stop distance; the calculator maintains constant dollar risk automatically.