Sunday 28 April 2024

Initial Test of Trading Forex News Announcements

My first test of trading forex news announcements is to test the efficacy of breakouts immediately following a news announcement related to the US dollar, specifically, only the high impact news as shown on the forexfactory calendar in red. The intention would be to capture some of the profit available from the big movements resulting from surprise news or simply market manipulation around these new events.

Rather than conduct a standard back test of a specific set of entry/exit rules to produce a single equity curve and test metrics, I decided to conduct a Monte Carlo simulation of R multiple returns, given that a news breakout occurred, across the following forex major pairs with USD as one of the pair, i.e. EUR-USD, GBY-USD, USD-CHF, USD-JPY, AUD-USD, NZD-USD and USD-CAD. I assumed that all the above pairs would collectively constitute one trade in the USD with a 1% risk in total, so each pair was allocated a 1/7th of 1% risk R multiple for each and every USD news announcement. 

Whether a breakout occurred or not, the R multiple risk, and whether or not the trade would have been ultimately profitable was independently simulated thus for each of the above pairs:

  1. On the 10 minute OHLC bar close immediately prior to the time of the news announcement a simulated buy order and a sell order were placed a distance of 1x the close to close variance above and below the bar close, this variance being determined by the output of my kalman_ema function
  2. The 1/7th of 1% risk R multiple was taken as the distance between these two entry orders, with each entry order having an attached protective stop-loss at the other entry order's level.
  3. On the next 10 minute OHLC bar, assumed to be the bar that should show the reaction to the news, if neither of the entry orders are hit it is assumed that no trade would have taken place. This would be functionally equivalent to cancelling the entry orders 10 minutes after placing them if no news reaction in price occurs.
  4. If the next 10 minute bar hits both entry levels, it is assumed that a whipsaw trade would have occurred and this is booked as a -1R losing trade. In all the simulations that follow, this trade will always be a -1R loss.
  5. If neither of the conditions in 3 or 4 above are met, it follows that one of the entry levels would have been hit and not stopped out on the entry bar. In this case, the maximum favourable excursion (MFE) of the high (for long entries) or low (for short entries) over the next 24 10min OHLC bars (4 hours) is recorded in terms of its R multiple value.
  6. Simultaneously with 5 above, it is recorded whether or not at any time in this forward looking 24 bar period this trade's entry protective stop level would have been breached. 
  7. The simulation now starts: all -1R trades from step 4 are kept as -1R losing trades.
  8. All trades that are flagged as having hit the stop level from step 6 have a random 50% chance of being booked as a -1R loss. This simulates being stopped out before the MFE is reached, or alternatively, completely messing up and missing a take profit opportunity and then riding the trade to a loss.
  9. All trades flagged from step 6 that are not booked as a -1R loss in step 8 have their MFE randomly multiplied by a value on the interval 0 to 1 to simulate being stopped out with a trailing stop. This also applies to trades from step 5 that do not hit stops identified in step 6. During the simulation this averages out to all profitable trades only achieving, on average, 50% of the maximum possible profit.
  10. All the trade results are cumulated into a total R multiple profit/loss across all the forex pairs per news announcement and then a percentage return equity curve is calculated and plotted, an example of which is shown next, with a log scaled y-axis and a thousand Monte Carlo replications. 

This following chart is the accompanying drawdown chart to the above equity curves chart, expressed as a percentage drawdown of the on-going, equity curve high water mark on the y-axis.
Taking the average equity curve ending value and the nth root of the number of trades, the average expected, cumulated R multiple return per news announcement is approximately 0.38R profit per 1R risk.
The above was not intended to be a test of a specific rule set per se, but rather a test of whether or not attempting to trade forex news announcements could be profitable. What the above shows is that essentially random exits could be profitable exits for a news breakout system, and so the assumption must be that intelligent exits, either take profit or stop loss, coupled with breakouts would make a viable trading system.
More in due course. 

Friday 19 April 2024

Trading Forex News

This post, as the title suggests, is about trading forex news releases and, incidently, is a small update to the appearances of my PositionBook chart and OrderLevels chart.

I recently came across this forexfactory post which shows how to download the underlying data for the forexfactory calendar, a screenshot of which is shown immediately below, and I thought I would look into the idea of trading around forex news

releases. If you look carefully at the screenshot you will see that at 2.30pm (CET) there was a high impact (red folder icon) news release regarding the Canadian dollar (CAD) which came in under expectations. The following OrderLevels chart
and PositionBook chart
clearly show the big move that immediately followed this news release (CAD weakness). The OrderLevels chart also shows the accumulation of sell orders (red background colour) that would have been an almost perfect take profit level for the day, whilst the PositionBook chart shows the accumulation of long positions (blue background colour) during the sideways movement that preceded the news release. These two charts both show the above mentioned appearance update resulting from the use of the b2r colormap function.
The following "overview" chart shows that the big move in the USDCAD forex pair was
definitely the result of this CAD weakness rather than USD strength (see the two rightmost currency strength charts).

Having finally "scratched the itch" of getting my PositionBook charts sorted out, my next project is to investigate the possibility of creating a forex news release trading methodology.
More in due course.

Tuesday 9 April 2024

A "New" Use for Kalman Filter on Price Time Series?

During the course of writing this blog I have visited the idea of using Kalman filters several times, most recently in this February 2023 post. My motivation in these previous posts could best be described as trying to smooth price data with as little lag as possible, i.e. create a zero-lag indicator. In doing so, the model most often used for the Kalman filter was a physical motion model with position, velocity and acceleration components. Whilst these "worked" in the sense of smoothing the underlying data, it is not necessarily a good model to use on financial data because, obviously, financial data is not a physical system and so I thought I would apply the Kalman filter to something that is ubiquitously used on financial data - the Exponential moving average.

Below is an Octave function to calculate a "Kalman_ema" where the prediction part of the filter is just a linear extrapolation of an exponential moving average and then this extrapolated value is used to calculate the projected price, with the measurement being the real price and its ema value.

## Copyright (C) 2024 dekalog
## This program is free software: you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## GNU General Public License for more details.
## You should have received a copy of the GNU General Public License
## along with this program.  If not, see .

## -*- texinfo -*-
## @deftypefn {} {@var{retval} =} kalman_ema (@var{price}, @var{lookback})
## @seealso{}
## @end deftypefn

## Author: dekalog 
## Created: 2024-04-08

function [ filter_out , P_out ] = kalman_ema ( price , lookback )

## check price is row vector
if ( size( price , 1 ) > 1 && size( price , 2 ) == 1 )
 price = price' ;

P_out = zeros( numel( price ) , 2 ) ;

ema_price = ema( price , lookback )' ;
alpha = 2 / ( lookback + 1 ) ;

## initial covariance matrix
P = eye( 3 ) ;

## transistion matrix
A = [ 0 , ( 1 + alpha ) / alpha , -( 1 / alpha ) ; ...
       0 , 2 , -1 ; ...
       0 , 1 , 0 ] ;

## initial Q
Q = eye( 3 ) ;

## measurement vector
Y = [ price ; ...
       ema_price ; ...
       shift( ema_price , 1 ) ] ;
Y( 3 , 1 ) = Y( 2 , 1 ) ;

## measurement matrix
H = eye( 3 ) ;

## measurement noise covariance
R = eye( 3 ) ;

## container for Kalman filter output
filter_out = zeros( size( Y ) ) ;
errors = ones( 3 , 1 ) ;

for ii = 2 : size( Y , 2 )

  X = A * filter_out( : , ii - 1 ) ;
  P = A * P * A' + Q ;

  errors = alpha .* abs( X - Y( : , ii ) ) + ( 1 - alpha ) .* errors ;

  IM = H * X ; ## Mean of predictive distribution
  IS = ( R + H * P * H' ) ; ## Covariance of predictive mean
  K = P * H' / IS ; ## Computed Kalman gain
  X = X + K * ( Y( : , ii ) - IM ) ; ## Updated state mean
  P = P - K * IS * K' ; ## Updated state covariance

  filter_out( : , ii ) = X ;
  P_out( ii , 1 ) = P( 1 , 1 ) ;
  P_out( ii , 2 ) = P( 2 , 2 ) ;

  ## update Q and R
  Q( 1 , 1 ) = errors( 1 ) ; Q( 2 , 2 ) = errors( 2 ) ; Q( 3 , 3 ) = errors( 3 ) ;
  R = Q ;


filter_out = filter_out' ;

Using this for smoothing either the price or the ema has no utility, but a by-product of the filter is the Covariance matrix from which it is possible to plot bands around the price series. The following chart shows the bands for various ema alpha values corresponding to various Fibonacci sequence length look backs for the ema alpha value.  
This next chart, for purposes of clarity, shows the "Golden Cross" lengths of 50 and 200
and this final chart shows an adaptive look back length which is a function of the instantaneous measured period (see here or here) of the underlying data.

Despite the wide range of the input look back lengths for the ema, it can be seen that the covariance bands around price are broadly similar. I can think of many uses for such a data driven but basically parameter insensitive measure of price variance, e.g. entry/exit levels, stop levels, position sizing etc.

More in due course.