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Rotational trading is a kind of backtest where you trade by switching positions between various symbols based on their relative score instead of traditional buy/sell/short/cover signals.

Since there are no signals used, only PositionScore assigned to given symbol matters.

It is worth noting that in case of rotational test, the Positions field in General tab of the Analysis settings is ignored. It is only used for regular backtests that use actual buy/sell/short/cover signals.

In the rotational mode the trades are driven by values of PositionScore variable alone.

In particular:

• higher positive score means better candidate for entering long trade
• lower negative score means better candidate for entering short trade

As you can see the SIGN of PositionScore variable decides whenever it is long or short.

Therefore – if we want to test long-only system in rotational backtesting mode, then we should use only positive values in PositionScore variable. For example – if we are trading a system, which uses 252-bar rate of change for scoring purposes:

Then, to trade only long positions, we should change PositionScore defintion for example to:

This way our scores will remain positive and that will effectively disable short trades.

More information about the rotational mode of the backtester can be found in the manual: http://www.amibroker.com/guide/afl/enablerotationaltrading.html

Filed by Tomasz Janeczko at 9:59 pm under General
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One common issue that surfaces pretty often is the lack of full understanding of differences between 32-bit and 64-bit versions of AmiBroker among users. This article tries to explain some of the most important bits.

WHICH VERSION DO I HAVE?

To find out which version you have installed just go to Help->About window. It clearly says “32-bit” or “64-bit” in the About window.

OPERATING SYSTEM COMPATIBILITY

32-bit version of AmiBroker is compatible with BOTH 32-bit and 64-bit Windows.
64-bit version of AmiBroker is compatible with 64-bit Windows ONLY.

32-bit version running on 64-bit OS can fully utilize as much as 4GB of RAM for the program data.
The rest of RAM is used for OS, file system cache, system libraries, etc.
64-bit can theoretically use all RAM available but Windows itself has some limits (see Microsoft web pages for details)

More on OS system compatibility can be found here: http://www.amibroker.com/guide/compat.html

REGISTRATION / ACTIVATION KEY

There are separate activation keys for 32-bit and 64-bit version. The key for 32-bit version is ABReg.exe, while the key for 64-bit version is named ABReg64.exe. If you apply wrong key (32-bit key for 64-bit application or vice versa), you will not get any error message but the application will still show “Unregistered”. So make sure you apply 32-bit key (ABReg.exe) to 32-bit application and 64-bit key (ABReg64.exe) to 64-bit application.

Also note that 64-bit key is available only to those who registered “Professional Edition”.

DATA SUPPORT

32-bit version offers the widest selection of supported data sources (all listed here: http://www.amibroker.com/guide/h_quotes.html )

Many 3rd party data sources that are not listed above come in 32-bit only.

64-bit offers limited support for data sources due to the fact that 64-bit support requires 64-bit API from data vendor, and this is not always available.

For more information:
http://www.amibroker.com/guide/compat.html

Typically if you put 3rd party data vendor DLL into “Plugins” directory and it does not show up in the data source list it means that its bitness is wrong (see below for more info).

PLUGIN COMPATIBILITY

Because of Windows OS limitations, 32-bit application is not able to load 64-bit DLLs and 64-bit application is not able to load 32-bit DLLs. In other words the “bitness” of application and DLLs must match. This has wide consequences with respect to plugins. Since plugins are just DLLs (dynamic load libraries), if you want to use a plugin you need to make sure it matches the bitness of your application. As majority of 3rd party plugins come only in 32-bit, so 32-bit version of AmiBroker offers widest selection of data plugin support.

FILE FORMAT COMPATIBILITY

We have put a lot of effort into making files compatible between 32-bit and 64-bit versions, so at the moment all formulas (AFL), project files (APX), all binary databases, layouts, watch lists are all 100% binary compatible between 32-bit and 64-bit versions, as long as they are smaller than 4GB. The only exception are DLLs (plugins) which are different for 32-bit and 64-bit as mentioned above.

PERFORMANCE

Generally speaking 64-bit offers pretty much same performance as 32-bit version. The difference in speed is marginal. The only true advantage of 64-bit versions is ability to address more than 4GB of RAM and support larger data sets.

PRECISION

Contrary to ‘common sense’, 64-bit applications are not more precise. Due to Intel/AMD/Microsoft decision the support for extended double 80-bit floating point (x87 FPU) has been dropped in 64-bit compilers and replaced by less accurate 64-bit floating point SSE2 for sake of speed. That is why you may see some speed up in 64-bit application. 32-bit code computes all results with internal 80 bit accuracy due to the use of 80 bit FPU unit. 64-bit does so with at most 64-bits. Also the ‘old’ x87 FPU handles way more instructions in hardware (like transcendentals), while new SSE2 only has basic math and all more complex functions are implemented in runtime library. While we are building both versions from the very same C/C++ source code and are striving to provide same results from all functions, these architectural differences can cause that output of 32-bit version is more precise.

More on floating point arithmetic can be found here: http://www.amibroker.com/kb/2010/07/20/about-floating-point-arithmetic/

Filed by Tomasz Janeczko at 8:35 pm under Troubleshooting
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When we want to develop a trading system, which enters only N top-scored symbols from each of the sectors, industries or other sub-groups of symbols ranked separately, we should build appropriate ranks for each of such categories. This can be done with ranking functionalities provided by StaticVarGenerateRanks function.

The formula presented below iterates though the list of symbols included in the test, then calculates the scores used for ranking and writes them into static variables. The static variables names are based on category number (sectors in this example) and that allows to create separate ranks for each sector.

Our test should be applied to a watchlist, which contains all symbols we want to include in our ranking code:

Running the exploration will show two top-ranked symbols for each of the sectors:

We can also change Filter variable definition to

and show all ranked symbols instead.

Such ranking information can be used in backtest and sample rules included at the end of the code use rank information to allow only two top-scored symbols to be traded.

Filed by Tomasz Janeczko at 1:22 am under General
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When you back-test a trading system, you may sometimes encounter trades marked with (6) exit reason, showing e.g.: Short (6) or Short (ruin) in the trade list as in the picture below:

As explained in the this Knowledge Base article: http://www.amibroker.com/kb/2014/09/24/how-to-identify-which-signal-triggers/ such identifier tells us that the trade was closed because of the ruin stop activation.

A ruin-stop is a built-in, fixed percentage stop set at -99.96%, so it gets activated if your position is losing almost all (99.96%) of its entry value. It almost never occurs in long trades, but it may be quite common if your trading system places short trades without any kind of maximum loss stop. Imagine that you short a stock when its price is $10, then it’s price rises to $20 (twice the entry price). When you buy to cover the position you must pay $20 per share, which means that your loss on this trade is $10 per share ($20-$10). This means 100% loss (as per entry value). If you placed such a trade with all your capital you would be bankrupt. That is why this stop is called “ruin stop”. Unfortunately, by the nature of short selling, the gains are limited to 100% (when stock price goes down to zero) but losses are virtually unlimited.

So what to do to prevent exits by ruin stop?

The best idea is to just place proper max. loss stop at much smaller percentage (such as 10% or 20%) depending on what your risk tolerance is, to limit drawdowns and decrease the chance of wiping your account down to zero.

If, for some weird reason, you want to turn OFF this built-in stop, you can do so using this code:

but it is highly discouraged, because when you wipe your account down to zero (or even below zero) it makes no point to run back-test any further. Instead of disabling this feature you should place proper, tighter maximum loss stop.

Filed by Tomasz Janeczko at 4:04 pm under Stops
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In addition to regular percent or point based stops, AmiBroker allows to define stop size as risk (stopModeRisk), which means that we allow only to give up certain percent of profit gained in given trade. The picture presented below visualizes a risk-mode trailing stop using 35% risk size. Since at the very beginning of the trade profits may be very low (and potentially triggering unwanted exits), this type of stop is best to use with validFrom argument, which allows to delay stop activation by certain number of bars.

The blue line on top represents highest high since entry, while red line shows the stop level calculation, yellow area shows the bars, where our stop has become active:

The above levels were calculated with the following code:

Filed by Tomasz Janeczko at 6:45 am under Stops
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The problem is as follows: during multiple-symbol Scan (or any other multi-threaded Analysis operation) we want to create a single, shared file and append content generated from multiple symbols to it.

There are two things that we must consider if we are running in multiple treaded scenario.
1. If we want to get just single-run results, before appending content to the file, we need first to delete file generated in previous runs.

2. We have to take care to open the file in share-aware mode so multiple threads do not write at the same time (preventing corruption).

A sample formula is presented below.

One important thing to remember is that in multi-threaded environment threads execute independently and there is no guarantee they will all execute sequentially, so the order of items (symbols) in the file may not be alphabetical.

If we want strictly sequential execution, then we must limit ourselves to just running in single-thread. A single-thread execution in New Analysis window can be achieved by placing the following pragma call at the top of the formula.

#pragma maxthreads limits the number of parallel threads used by New Analysis window. This command is available in AmiBroker version 6 or higher.

Filed by Tomasz Janeczko at 6:47 am under Analysis
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Charting ratios between the prices of two symbols can easily be done with AmiBroker. For this purpose we can use Spread built-in formula available in Charts window:

Then select the style as Ratio:

The primary symbol (Symbol1) is the one selected in the chart window, the other symbol (Symbol2) is defined in the Parameters window, as presented in the above screenshot.

It is also possible to create such ratio chart programmatically in AFL using the following code:

Symbol1 and symbol2 names in the above code need to be replaced with the actual symbol names from our database we want to use.

Filed by Tomasz Janeczko at 7:10 am under Charting
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Built in HHV and LLV functions allow to read highest high or lowest low of n-past bars. If we want to refer to future values, there is an easy way to do it using simple Ref function and just shift HHV or LLV reading from N-bars ahead. A ready to use function showing such approach is presented below:

And here is the chart produced by the formula above:

Filed by Tomasz Janeczko at 7:25 am under Indicators
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When we want to find out how many symbols belong to given category (such as watchlist) then for manual inspection, it is enough to hover the mouse cursor over the particular category name in the Symbols window and the information will be shown in a tooltip:

If we want to check such information using AFL code, we could read the list of symbols returned with CategoryGetSymbols and by counting commas (which separate symbol names) find out the number of tickers.

A reusable function is presented below:

Filed by Tomasz Janeczko at 7:26 am under AFL,Data
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When we use File->Import ASCII to import data, we can choose import file format using one pre-defined import format definitions. As it is explained in the manual (http://www.amibroker.com/guide/d_ascii.html) it is also possible to create our custom import definitions to match data we are trying to import. This article explains all the required steps.

The easiest method to create import definition is to use File->Import Wizard. In the first page, select at least one file in the format we want to import and on the second page configure columns:

This all easy when we are importing quotation data, but when we are importing non-quotation data such as category assignments, we can not select appropriate columns using Import Wizard. In such case we need to type-in appropriate $FORMAT command in the “Additional commands” field of Import Wizard.

For example if we have file with categories like this:

"DDD","3D Systems Corporation","Technology","Computer Software: Prepackaged Software",1
"MMM","3M Company","Health Care","Medical/Dental Instruments",1
"WBAI","500.com Limited","Consumer Services","Services-Misc. Amusement & Recreation",1
"WUBA","58.com Inc.","Technology","Computer Software: Programming, Data Processing",1
"AHC","A.H. Belo Corporation","Consumer Services","Newspapers/Magazines",1
"ATEN","A10 Networks, Inc.","Technology","Computer Communications Equipment",1
"AIR","AAR Corp.","Capital Goods","Aerospace",1
"AAN","Aaron's,  Inc.","Technology","Diversified Commercial Services",1

We need to add the following commands in the “Additional commands” field of Import Wizard

$FORMAT Ticker,FullName,SectorName,IndustryName,Group
$OVERWRITE 1
$CLEANSECTORS 1
$SORTSECTORS 1

First line tells AmiBroker the column meaning, second line tells it to overwrite existing data. Last two lines tell AmiBroker to wipe existing category structure and sort imported sectors alphabetically. Be sure NOT to specify $CLEANSECTORS command when you do NOT want to wipe existing category structure.

We also need to mark “No quotation data” box in the second page of Import wizard to tell AmiBroker that the file that we are importing does not contain quotes and it should switch off all price checking.

Finally, in the last step of the wizard save the format definition:

Once we do this, next time we use File->Import ASCII a new selection My own format will appear in the Files of type combo box in the file selector dialog.

It is worth noting that import definitions are plain text files that are stored in “Formats” subfolder of AmiBroker directory, and the list of available import definitions that appears in “Files of type” combo box, is also a plain text file called “import.types” that is located in the same subfolder. So, advanced users may also modify those files directly using plain text editor such as Notepad. It is all explained in great detail in the manual http://www.amibroker.com/guide/d_ascii.html

Filed by Tomasz Janeczko at 8:11 am under Data
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