# Month: April 2013

### Mining for Three Day Candlestick Patterns

I’ve been thinking a lot about candlestick patterns lately but grew tired of trying to generate ideas and instead decided to mine for them. I must confess I didn’t expect much from such a simplistic approach, so I was pleasantly surprised to see it working well. Unfortunately I wasn’t able to discover any short set-ups. The general bias of equity markets toward the upside makes it difficult to find enough instances of patterns that are followed by negative returns.

The idea is to mine past data for similar 3 day patterns, and then use that information to make trading decisions. There are several choices we must make:

• The size of the lookback window. I use an expanding window that starts at 2000 days.
• Once we find similar patterns, how do we choose which ones to use?
• How do we measure the similarity between the patterns?

To fully describe a three day candlestick pattern we need 11 numbers. The close-to-close percentage change from day 1 to day 2, and from day 2 to day 3, as well as the positions of the open, high, and low relative to the close for each day.

To measure the degree of similarity between any two 3-day patterns, I tried both the sum of absolute differences and the sum of the squared differences between those 11 numbers; the results were quite similar. It would be interesting to try to optimize individual weights for each number, as I imagine some are more important than others.

The final step is to select a number of the closest patterns we find, and simply average their next-day returns to arrive at an expected return.

Expected vs realized returns for SPY, 50 closest patterns by absolute difference. Numbers above the bars indicate the number of instances in each bucket.

How do we choose which patterns are “close enough” to use? Choose too few and the sample will be too small. Choose too many and you risk using irrelevant data. That’s a number that we’ll have to optimize.

Histogram of expected return estimates for different sample sizes.

When comparing the results we also run into another problem: the smaller the sample, the more spread out the expected return estimates will be, which means more trades will be chosen given a certain minimum limit for entry. My solution was to choose a different limit for trade entry, such that all sample sizes would generate the same number of days in the market (300 in this case). Here are the walk-forward results:

The trade-off between sample size and relevance is clear, and the “sweet spot” appears to be somewhere in the 50-150 range or so, for both the absolute difference and squared difference approaches. Depending on how selective you want to be, you can decrease the limit and trade off more trades for lower expected returns. For me, 30 bp is a reasonable area to aim for.

A nice little addition is to use IBS by filtering out any trades with IBS > 50%. Using squared differences, I select the 50 closest patterns. When their average next-day return is greater than 0.2%, a long position is taken. The results are predictably great:

The IBS filter removes close to 40% of days in the market yet maintains essentially the same CAGR, while also more than halving the maximum drawdown.

Let’s take a look at some of the actual patterns. Using squared differences, the 50 closest patterns, and a 0.2% limit, the last successful trade was on February 26, 2013. The expected return on that day was 0.307%. Here’s what those 3 days looked like, as well as the 5 closest historical patterns:

As you can see below, even the 50th closest pattern seems to be, based on visual inspection, rather close. The “main idea” of the pattern seems to be there:

Here are the stats from a bunch of different equity index ETFs, using square differences, the 50 closest patterns, 0.2% expected return limit and the IBS < 0.5 filter.

The 0.2% limit seems to be too low for some of them, producing too many trades. Perhaps setting an appropriate limit per-instrument would be a good idea.

The obvious path forward is to also produce 2-day, 4-day, 5-day, etc. versions, perhaps with optimized distance weighting and some outlier filtering, and combine them all in a nice little ensemble to get your predictions out of. The implementation is left as an exercise for the reader.

### A Quick Look at Bitcoin Returns

Bitcoin seems to be all the rage these days, and I’m jumping on the bandwagon. Quandl tweeted about their bitcoin data today so I decided I’d have a look at it. I have tested a bunch of popular/”standard” ideas, and the results aren’t really surprising, though they do illuminate the trend-y (bubbl-y) character of the bitcoin market. BTC prices do not revert like equities but show strong momentum, both in the short and medium term. IBS is useless, while trend following works like it does everywhere else.  The (daily) data covers the period from 17/7/2010 to today.

## Descriptive Stats

The mean simple daily return has been 1.012%, while the annualized standard deviation has been 121.70%. The distribution of returns is obviously fat-tailed (with a kurtosis of 8.62), though somewhat surprisingly (to me at least), slightly positively skewed (0.76).

## Up/Down Streaks

Strong up streaks tend to be followed by high returns over the medium term, and there has been a surprisingly large number of these streaks given the small amount of data available.

## IBS

IBS does not appear to have any predictive value when it comes to bitcoin returns.

## RSI(3)

No mean reversion to be found here. Using a 3-period Cutler’s RSI, next-day bitcoin returns are 0.392% when RSI(3) is below 20, and 1.763% when it is above 80. The story is pretty much the same if you go for a medium term length for the RSI: high values beget high returns, with no mean reversion in sight.

## Simple Trend Following

The strong trends that bitcoin has shown would have been very profitable to any trend followers. Going long at a new 50-day high close (with an exit at a new 25-day low close), and vice-versa for short positions, would have yielded these equity curves:

## Day of the Week

Before you jump in, keep in mind that this sort of market can change character very quickly, especially after a big bubble pop. Also consider the fees: Mt. Gox, the most popular exchange, charges an obscene 120 basis points per roundtrip. There are some brokers that will allow you to short bitcoins, and there even appear to be some thinly-traded options and currency futures available…I imagine there are gigantic inefficiencies in the pricing of these instruments (though their legality is probably questionable).