*** 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.

Mechanical Investing FAQ

---

Contact Shrewd'm
Contact the developer of these message boards.