Three Trading “Truths” Quantified

trading truths

I want to discuss three trading “truths” that I often hear but when I finally got into testing ideas found them to be myths. These discoveries were instrumental in turning my trading around.

For those that know my story, it was not all roses and rainbows – what trading story is?!? I actually “learned” about a lot of traders from online sources, chat rooms, webinars, and eventually found the right circles to roam in after a LOT of trial and error. I was then lucky enough to land a job with a high frequency trading firm. I was quickly made to realize that much of what I thought trading “was” was most certainly false.

In an attempt to show me the light, a few of the quick trading axioms they wanted to disprove to me were simple “well known” trading ideas that have been around for years but were in fact large falsehoods. I quickly realized beyond this list of three examples that there must have been many, many more “trading truths” that were causing harm to my account and doing my trading aspirations a disservice.

I then realized the value in testing everything and quantifying my entire approach. It wasn’t until this point in my journey did I get out of the “rat race” of trading… the ups and downs, the barely consistent, always doing slightly better but not really getting anywhere trading most of the traders I meet today are going through.

I cannot stress the importance of testing everything and quantifying your edge. Investigate these trading axioms. Otherwise you will be stuck in randomness until your account walks to 0. For more on my journey check out this podcast I did, chatwithtraders.com/103. Below you will find my three favorite trading “truths” quantified.

Trading “Truth” #1 - Bearish Engulfing Candle

This one is great because many are familiar with Japanese candle stick patterns and the name implies such a negative move in price that one cannot help but to shift their bias to the downside. These candlestick patterns are often traders' first introduction to technical analysis.

The pattern is defined as a bearish candle that “engulfs” the range of the previous day. I also like to look for a negative close and preferably a close below the previous session’s low. Here are a few pictures of bearish engulfing candles.

The truth is that this pattern has been one of the most bullish (not bearish) 1-day signals for the SP500 over the past 15+ years. Did you know that the day following a bearish engulfing candle actually closes higher than 61.72% of the time in the SP500 futures and 65.33% of the time in SPY ETF? The day following a bullish engulfing candle only closes higher than 54.05% of the time in the SP500 futures and 51.70% of the time in SPY. You tell me why they’re named how they are!


Trading Truth #2 – Above a moving average is bullish and below is bearish

Most of the time this is true but it depends on the moving average, moving average length, and the market. I recently came across a few blogs that mentioned using a short term moving average as a sign to exit long market exposure and wait for sunnier days. In reality, this sounds great; however, analyzing the data this can be an extremely misleading “truth”.

Below is a chart plotting the equity curve if you would buy every close when the SP500 is BELOW the 8-period simple moving average (8SMA) and sell the next bar (repeating until above 8SMA). The second chart is if you were to buy every close when the SP500 is ABOVE the 8SMA and exit the next bar (repeating until below 8SMA). Yes, being below this moving average is actually better for long returns.

trading truths

Of course this is not true for all markets and moving averages, as mentioned. I pointed this out in another post on SeeItMarket where I dissected popular stocks and different moving average lengths here: https://www.seeitmarket.com/testing-moving-averages-popular-stocks-etfs-16809.

The point is that these trading truths like “above a moving average is bullish” and “below a moving average is bearish” need to be quantified and tested. It is important to stop thinking trading truths can be generalized to every market, timeframe, indicator value, etc. and just verify them yourself and you’ll be much better off!

Trading Truth #3 – Overnight Exposure is Risky

Sure earnings announcements and large unexpected news announcements typically happen after market close. Does this mean we should avoid trading overnight, if possible? So many want to day trade and be flat on the close that they miss a lot of gains from the overnight session (sometimes all of them).

Below you will see 30 top stocks where I breakdown their returns in the day session compared to the overnight session. The blue line signifies if you bought the open and sold the close the same day (day session), and the orange line signifies buying the close and selling on the next day’s open (simulating overnight exposure). As expected, there are no generalities in trading truths. Some stocks exhibit that most, if not all, returns come from the overnight.

In conclusion

Not all trading truths are “truths”. There are many that still have value! The edge is not in these truths but in determining the difference between a truth and a “truth”. Most do not take the effort to investigate these trading axioms found in trading books, blog sites, chat rooms, etc. If I have one goal then it is to make traders realize the value in testing everything – it is something I wish I would have started earlier. It is a super power to quickly test these ideas and trade/act accordingly!

I think many traders shy away from digging into the data because it requires effort and they think it will be a hard and arduous journey before they find some gold. But now I think it is increasingly easier than many may think.

That’s why Build Alpha’s main goal was (and still is) to make this type of testing easier for those with no programming skills or those tired of crunching endlessly in excel. The game is changing and things like this can be easily tested now. Today, trading just comes down to those who will put in the work and who won’t: this should greatly increase your odds for success if you’re part of the former group.

--By David Bergstrom from blog Buildalpha

About the Author Dave Bergstrom

My name is David Bergstrom, and I am the guy behind the Build Alpha software. I have spent many years researching, building, testing, and implementing market making and directional trading strategies for a high frequency trading firm. I am a self taught programmer who uses C++, C#, Python, Perl, Java and even TradeStation’s EasyLanguage. Most of my experience has led me to a series of repeatable processes to find, create, test, and implement trading ideas. Build Alpha is the culmination of this process from start to finish.

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