Ann: May 2022 Investment Update, page-13

Correct I stuffed up again.... I used NTA 2.07 instead of 2.17.

According to the prospectus, WGB uses the MSCI World Index Net (AUD) as benchmark to calculate its performance fee.
However on the performance table on WGB webpage, both MSCI World Index Net (AUD) and the MSCI World SMID (Small/Mid) Cap Index in AUD terms are used as benchmarks. It makes sense since as you mentioned they hold a lot of mid/small caps.

MSCI World Index Net (AUD) - VGS:ASX since 31st of May: -5.66% ---> ~NTA $2.0492
MSCI World SMID (Small/Mid) Cap Index (US) - WSML since 31st of May: -8.4%
USD/AUD: +3.5%
--> ~NTA $2.0572

So ~$2.05 NTA and at current SP that's about ~15% discount (if I did not screw up a year 5 maths calculation again....)