It’s nearly impossible to go a day in December without hearing the phrase “Santa Claus rally.” There is an impression that the market tends to rally into the end of the year, and that we can count on that. Many explanations have been proposed, ranging from managers marking their books to holiday goodwill to more quantitative reasons. In an earlier post, I made the arguments that the market was not a math problem, and that you don’t have to use a lot of advanced math to understand the markets. This is true, but math is a powerful tool. Used properly, it can help us see what is real in the market. To illustrate this point, let’s look at the Santa Claus rally, and ask two questions: First, is it real? Meaning, does the market really tend to go up into the end of the year? Second, if it is real, how has it performed over time? If we find something that has persisted for many years and appears to be stable, it’s probably much more likely to work this year.
To run this test, I used about 90 years of the Dow Jones Industrial Average because of the long data history. It is a reasonably good, but not great, proxy for the broad market—good enough for this purpose. I first took daily closes, then converted them to percent returns. Since daily returns tend to be small, I went one more step and converted them to basis points, just because it is easier to deal with a number like 2 than .0002. (A basis point is one one hundredth of a percent, so 1% = 100 bp, 0.1% = 10bp, etc.) Let’s work first of all with recent data. Here are some summary stats for all daily returns:

Be sure we understand what this table is telling us: There have been 3,019 trading days with an average daily return of 1 basis point (=.01%). The worst day was -7.87%, and the best day saw the market go up a little over 11% on that day. The important thing here is to understand the thought process: we need to know what “all” days look like as a control group, so we can contrast them with the days that have the specific condition we are interested in. In this case, let’s compare them to trading days in December, since that’s when Santa comes.

Now, this is getting interesting. December shows an average return almost seven times the average of all days in the year. Another thing to notice is that the standard deviation, which is a measure of how widely spread out values are, is smaller (though let’s not focus on the standard deviation for this post.) Not only are the daily returns larger, but we seem to know where they will be with more certainty (if this dataset shows tendencies that continue into the future.) Conventional wisdom (and seasonal analysis) tells us that volatility tends to contract into the end of the year; this table seems to support that. Let’s dig just a bit deeper, and look at what happens if we break out the last two weeks and the last week of the year separately.

Maybe we are a little bit less impressed here, but the effect does appear to hold. (Also not shown in this table is the closing print for the year has been higher than the open of the previous 4 weeks 75% of the time.) So, yes, Virginia, there is a Santa Claus rally, but wait… we are not done yet. Take a look at the following table, which reproduces this table in roughly 2 decade segments.

Now we start to see a clear pattern, and the truth is ugly for the Santa Claus rally. Each segment shows a weaker and weaker effect—the last week of the year, which since 2000 has yielded an average daily return of 0.05%, gave a 0.25% return in 1940-1959, and a whopping 0.4% (per day) in 1922-1939. By comparison, today’s effect is anemic. Probably the best way to put this is, “Yes, Virginia, there has been a Santa Claus, and if you were a good investor he probably brought you money. He probably even did this for decades and decades, but he seems to be getting tired, and I’m not sure we can count on him showing up next year, or the year after that. If we hang our hopes on Santa Claus in the market, it seems like we might be frustrated. There must be a better way.”
The Art & Science of Technical Analysis
At the End of the Year, a Time for Reflection
As we come to the end of the year, I want to encourage and challenge my readers to think about their trading performance. Working toward trading competence is a path, not a destination. Whether you are an experienced trader who is very pleased with your performance, a struggling developing trader, or someone who has just begun her journey, I’d like you to spend a few hours in self-reflection and ask yourself a few simple, but profoundly important questions:
Thinking a bit deeper about these questions: What is your edge in the market? How do you know? If you are going to be successful trading, you absolutely must have an edge in the market. Money management is not an edge. Psychology is not an edge. An edge is something that lets you pull profits out of an extremely competitive market environment, that gives you some edge over the randomness that dominates price movements. How do you know what your edge is? If you can’t answer these questions, you don’t have any business putting risk on in the markets. You do not have an edge because you bought a book or took a training course, no matter how much money you paid or who taught you. You must have sufficient math skills to understand probability and randomness and truly understand your edge in the market.
How stable/strong is your edge? There are very, very few persistent edges in the market. Most come and go, and may not be reliable in the future. How is your edge on this scale? Again, how do you know?
What do you need to work on? Most people tend to focus on what they do best, and to avoid focusing on their weaknesses. This makes sense in some cases, and it certainly is easier psychologically. However, from a performance perspective, and especially for someone developing skills, finding and working on your weaknesses is often the key to the fastest progress. If you are a beginner, you may be doing many things wrong, but a good mentor or coach can point you to the most pressing issues you should address first. Commit to finding your weaknesses and improving them, and watch your overall performance grow by leaps and bounds.
What do you do best? Yes, I think the majority of your time should be spent on addresses your weaknesses, but don’t neglect your strengths. Chances are, there are a few things you do really well. Know what those are, protect those strengths, and work to improve them. For beginners, it probably makes sense to focus most of your attention on strengthening weaknesses and improving faults. For more experienced practitioners, the path to improvement is often marked by your strengths. Find them, nurture them, and watch your performance grow.
What can you do better? No matter who you are, how good of a trader you are, or how good your year was, there’s always something you can improve. Make a concrete list of the three top things you want to work on, and focus on those early next year. This is not a vague “New Year’s resolution”—it is a concrete action plan for growing as a trader.
Follow @AdamHGrimes