No. of Recommendations: 5
*** 3. Historical Universe Size ***
From 2016 to 2025, GTR1 and P123 had about the same number of stocks in {UnivZero}. In 2021, the number of stocks increased about 20%, and the ratio of P123 to GTR1 stocks increased from 96% to 99%.
UnivZero from to P123 GTR1 ratio P:G
avg 1/4/2016 8/6/2020 4707 4881 96%
avg 2/17/2022 11/28/2025 5687 5732 99%
increase 21% 17%
The number of missing stocks gradually decreasing over time could signify some survivorship bias. The average difference between the GTR1 and P123 {UnivZero} stock counts is:
Year AvgMissing
2016 186
2017 178
2018 172
2019 167
2020 178
2021 144
2022 51
2023 46
2024 39
2025 42
P123 improved coverage in 2021. There might be a minor survivorship bias of about 10 stocks over 4 years (out of about 5000 stocks including penny stocks and nano-caps).
Similar results are seen with the screens {UnivOne} and {Base}. Coverage is similar in GTR1 and P123.
screen date P123 GTR1 ratio P:G
UnivZero 1/4/2016 4829 5020 96%
UnivOne 1/4/2016 4063 3986 102%
Base 1/4/2016 2597 2601 100%
UnivZero 11/28/2025 5402 5458 99%
UnivOne 11/28/2025 3927 3784 104%
Base 11/28/2025 2829 2789 101%
{UnivOne} and {Base} have lower GTR1 counts because of fewer stocks in the SIP database.
