The Great Paradox in Markets

Over the past few weeks, the stock market has moved from an oversold extreme to an overbought extreme, a function of the violent December sell-off followed by the near-vertical rally.

On December 24, the S&P 500 closed at 2,351, down 14.8% on the month and 20% from its all-time high. Notably, the NYSE McClellan Oscillator (a market breadth indicator) hit one of its lowest levels in the past 20 years: -109.61.

NYSE McCllellan Oscillator graph

Note: Data on $NYMO (McClellan Oscillator) is from and goes back to June 1998.

By all accounts, the market was extremely oversold. What happens when the market is extremely oversold?

It tends to bounce, with above-average forward returns over the next 12 months (+20.7% vs. +7.9% for all readings) and a higher probability of a positive return (up 87% of the time over next 12 months vs. 76% for all readings).

S&P 500 Average forward total returns 1998 to 2018 chart

Note: Highlighted area in the table represents the bottom 1% of all $NYMO readings, or the most short-term oversold data points going back to June 1998.

And bounce it did, with the S&P 500 rallying 10% in the next 2 weeks. What happened to the McCllellan Oscillator? It shifted 180 degrees, hitting its 2nd highest level in the past 20 years on Jan 9: +117.76.

Image of NYSE McCllellan Oscillator

By all accounts, the market was now extremely overbought (on a short-term basis, at least). What happens when the market is extremely overbought?

It tends to continue to rally, with above-average returns over the next 12 months (+20% on average vs. +7.9% for all readings) and a higher probability of a positive return (up 98% of the time over the next 12 months vs. 76% for all readings).

Differential values of S&P500 average forward total returns chart

Note: Highlighted area in the table represents the top 1% of all $NYMO readings, or the most short-term overbought data points going back to June 1998.

Are these results intuitive? Certainly not.

It is one of the great paradoxes in markets that both extreme oversold and extreme overbought conditions tend to be followed by above-average returns. How is this possible? Likely because extreme strength begets strength (momentum) while extreme weakness does the same (mean reversion). Momentum and Mean Reversion are the most powerful forces in markets, and they exist because investors overreact and underreact to new information, again and again.

What will happen from here? Nobody knows. The best we can say in markets is what is more or less likely to happen, and those odds are forever changing.

When the market has been this extremely overbought in the past, it has tended to continue its ascent with above-average performance. But alas, tends to is far from always. There are a number of examples where the market suffered nasty declines after extreme overbought readings (Feb/Nov/Dec 2008, Jan 2009, Jul 2011, etc.)…

NYMO readings and forward S&P 500 total returns chart

These “exceptions” should come as no surprise, for there is no holy grail in markets that can predict the future with perfect foresight. There are only probabilities. Accepting this reality as a trader or investor can go a long way.


Related Posts:

What Happens when Stocks Are Extremely Oversold?

The 5 Kinds of Bounces



Charlie Bilello is the Director of Research at Pension Partners, LLC, an investment advisor that manages mutual funds and separate accounts. He is the co-author of four award-winning research papers on market anomalies and investing. Charlie is responsible for strategy development, investment research and communicating the firm’s investment themes and portfolio positioning to clients. Prior to joining Pension Partners, he was the Managing Member of Momentum Global Advisors. He previously held positions as a Credit, Equity and Hedge Fund Analyst at billion dollar alternative investment firms.

Charlie holds a J.D. and M.B.A. in Finance and Accounting from Fordham University. He has also done a B.A. in Economics from Binghamton University. He is a Chartered Market Technician (CMT) and also holds the Certified Public Accountant (CPA) certificate.

In 2017, Charlie was named the StockTwits Person of the Year. He has been named by Business Insider and MarketWatch as one of the top people to follow on Twitter. His work has also been featured in Barron’s, Bloomberg, and the Wall Street Journal.

You can follow Charlie on twitter here.


Pension Partners, LLC is a federally registered investment adviser under the Investment Advisers Act of 1940. Registration as an investment adviser does not imply a certain level of skill or training. The oral and written communications of an adviser provide you with information about which you determine to hire or retain an adviser. For more information about Pension Partners please visit: and search for our firm name.

The information herein was obtained from various sources. Pension Partners does not guarantee the accuracy or completeness of such information provided by third parties. The information given is as of the date indicated and believed to be reliable. Pension Partners assumes no obligation to update this information or to advise on further developments relating to it.

The S&P 500 is an American stock market index based on the market capitalizations of 500 large companies having common stock listed on the NYSE or NASDAQ. An index is an unmanaged portfolio of specific securities. It is often used as a benchmark in judging relative performance of certain asset classes. An index does not charge management fees or brokerage expenses. No such fees or expenses were deducted from the performance shown.

Past performance is not indicative nor a guarantee of future results.


This writing is for informational purposes only. It does not constitute an offer to sell, a solicitation to buy, or a recommendation regarding any securities transaction. It also does not offer to provide advisory or other services by Pension Partners, LLC in any jurisdiction in which such offer, solicitation, purchase or sale would be unlawful under the securities laws of such jurisdiction. The information contained in this writing should not be construed as financial or investment advice on any subject matter. Pension Partners, LLC expressly disclaims all liability in respect to actions taken based on any or all of the information on this writing.


Comments are closed.