The ASX price is whatever it is and is determined as usual by...

The ASX price is whatever it is and is determined as usual by trades on the ASX. The total company shares can be found from https://money.tmx.com/en/quote/NXE/key-data. Since NXG (aka NXE) is a Canadian company you need to get the full number of shares issued and listed from the Toronto Stock Exchange and not the ASX. The ASX only tells you the number of CDIs that have been created for listing on the ASX (these are only a minority of the total issued shares). Once you have the complete number of shares then you can calculate the market cap.in A$ in the usual way (this will be a much larger value that what the ASX shows as market cap. because the ASX is only considering CDIs listed on the ASX. Since CDIs are created on a 1 for 1 basis, every CDI corresponds to a single share in the Canadian company. Do not add the CDIs to the TSX value because a CDI is created from an existing NXE share and you do not want to double count.

You can determine any gap in value between the ASX and the TSX share prices by applying the A$ to C$ exchange rate. Lately, the ASX shares have been selling well above the TSX value. Probably because NXG raised US$110M in convertible debentures from Queen’s Road Capital Investment Ltd and Soul Pattinson so that AUS institutions think it is a good deal and want to join the party. Personally, I think they have become overvalued based on several factors, but that is my only my opinion.