Assessing the January Barometer Theory

Stocks tend to perform well if the first month of the year is positive

Senior Quantitative Analyst
Jan 29, 2020 at 8:04 AM
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Stocks were sailing smoothly for the first part of the year until investors balked after countries began taking action to contain the spread of the coronavirus. The S&P 500 Index (SPX) flirted with going negative on the year early in the week, but after yesterday’s bounce back, the index is safely above that level. Typically, a few points up or down wouldn’t matter for a longer-term forecast, but if you subscribe to the January Barometer theory, then it could be considered consequential.

The January Barometer theory is that the first month of the year sets the tone for the rest of the year. The idea that one month of trading can create momentum for the next 11 months seems absurd, but the data behind the theory is hard to ignore. This week I’ll show the compelling numbers behind the theory, look at it on a shorter-term basis, and finally layer in some sentiment to see if that changes anything.

January Barometer Data

Below is a table summarizing the performance of the S&P 500 Index from February through December, depending on whether January was positive or negative. Stocks have performed far better after a positive first month compared to a negative first month. The chart accentuates how much better the rest of the year has performed when January was positive. After a positive January, the blue line shows stocks have tended to steadily move higher for the rest of the year (other than a lull from mid-July through mid-October). After a negative January, however, stocks on average have tended to chop around the breakeven level; gaining around 2% for the rest of the year.

SPX past 50 years jan 28

January as a Short-Term Barometer

We know January has been a good indicator for the rest of the year, but what about the next month? How about for the rest of the first-half? Again, the numbers make a good case that January can predict the future.

Over the last 50 years, when January was positive, February was positive 70% of the time, gaining 1.12% on average. When January was negative, the index fell an average of 0.82% the next month and positive just 40% of the time. The second table shows returns through the rest of the first half. Without difficulty, stocks again outperformed when January was positive.

spx 2 jan 28

Chart Score as an Indicator

According to the weekly Investors Intelligence sentiment survey, there’s a lot of positive sentiment already built into stock forecasts. The editors at Investors Intelligence gather over 100 published stock newsletters and determine the percentage that are bullish and bearish on the market going forward (there’s a third designation for newsletters that are short-term bearish but longer-term bullish). So far this year, the percentage of bulls have outpaced the bears by about 41%. So, sentiment is very bullish by this metric. As contrarians, we would expect this to have bearish implications going forward.

The table below summarizes the returns from February through December after a positive January, depending on the amount of bullishness or bearishness in the Investors Intelligence poll through the first month of the year. When there’s significant optimism (defined here as a bulls minus bears spread of 35% or more), the S&P 500 averages a gain of just 5.88% for the rest of the year with about 71% of the returns positive. It’s not a bad return for the next 11 months, but it’s nowhere near the average double-digit gains with about 88% positive otherwise.

SPX After Positive January

Looking strictly at the numbers, bullishness in the Investors Intelligence survey means less in the short term. February averages a 1% gain with 71% of the returns positive when there’s significant optimism after a positive January. This is similar to what you see after any positive January.

SPX After Positive January (FEB)

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