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The week's question
In March 2025, in the thread "Re: OT, out", Umm asked the members: "Do you think it is because America is made up of magical soil that makes businesses based in America magically profitable?" This week it is put to everyone again. The button below opens the small thread re-asking it - read what others have said so far, then give your own answer as an ordinary reply.
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Investment Strategies / Mechanical Investing
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Author: rayvt ✧☼🐝🐝  😊 😞
Number: of 6243 
Subject: Flaws in timing with GTR1
Date: 06/15/26 6:47 PM
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No. of Recommendations: 5
Flaws in timing with GTR1

The way to run a screen is:
1) The night before trading day
**** Compute the IN/OUT timing signal
**** Generate the screen picks
2) On the morning of trading day
**** If the timing signal is OUT, sell everything and go to cash
**** If the timing signal is IN, do the sells & buys according to the screen picks.
3) Wait until the next trading day. Do not sell or buy or look at the timing.

The timing in the below GTR1 screen does not work this way. It is fundamentally flawed for the above steps.
I have looked at the GTR1 steps but until today I did not see.
The GTR1 field is "Close all liquid positions and hold cash on any market dates where ..."

GTR1 will go to cash and then to the investments on any day, regardless of where it is in the holding period.
We do not trade a screen that way.

BTW, GTR1 evidently imputes interest on cash.

Screen:
gtr1.net: GTR1 Backtester - nas100 top5 with BCC

For full details, check these two boxes
Portfolio Values: Download daily portfolio values for all cycles of the focus variant.
Signal Values: Download daily values of any defined signal fields for the focus variant.

Here are a few examples.
The first shows that it goes to cash and back to stocks in the middle of a holding period.
The second shows it going to cash in the middle of one holding period and then back to stocks in the middle of the next holding period.
There are even times where it would flip back and forth every few days.
Date       Value    day# in holding period        BCC signal
10/04/94 $88.88 8 IN
10/05/94 $91.76 9 IN
10/06/94 $90.11 10 OUT
10/07/94 $90.13 11 OUT
10/10/94 $90.16 12 OUT
10/11/94 $90.18 13 OUT
10/12/94 $90.19 14 OUT
10/13/94 $90.20 15 IN
10/14/94 $90.40 16 IN

11/19/07 $2,896.86 17 IN
11/20/07 $2,913.03 18 IN
11/21/07 $2,875.24 19 OUT
11/23/07 $2,875.72 20 OUT
11/26/07 $2,876.47 0 OUT
11/27/07 $2,876.71 1 OUT
11/28/07 $2,876.96 2 OUT
11/29/07 $2,877.20 3 OUT
11/30/07 $2,877.43 4 IN
12/03/07 $2,850.50 5 IN
12/04/07 $2,839.55 6 IN

Here are all the OUT periods, the number of days in a row of OUT and the number of times that occurred.
It was OUT for just 1 day 19 times. It was OUT for 10 days twice.
Half of the OUT periods were less than 18 days.
The holding period is 21 market days.
Sequential days     Count
out
1 19
2 7
3 8
4 2
5 2
6 4
8 1
9 1
10 2
15 1
17 1
24 1
28 1
35 1
39 1
40 1
43 1
49 1
52 1
55 1
120 1
196 1
246 1
413 1
635 1

If anybody wants to see the spreadsheet that gathers all this information, let me know and I'll upload it somewhere. Or email it to you.
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