I'd like to own some Novo Nordisk and my investment vehicle is a UK SIPP (pension) account.
There don't appear to be any Novo Nordisk listings directly on the UK, but there are many tickers listed on various non-UK stock exchanges (https://www.google.co.uk/finance?q=novo+nordisk&ei=oGnUVpG_BcPSugSaqLmQDA). Which of those listed would be most tax-efficient in this case, and how do I go about figuring that out on my own for future purchase considerations?
Please ignore the question of restrictions on where my SIPP might let me purchase stock -- I've got that covered. The question only pertains to tax efficiency of each particular ticker, with respect to holding in the UK. For example, I know that holding NOVO-B, which is listed on the CPH exchange, will cause a 27% pre-distribution tax withholding on any dividends for non-Danish stock holders. And because my holding will be in a SIPP, I have no way to claim that back either as a refund or as a tax credit on my UK taxes. I don't know about cap gains taxation for NOVO-B though. And I'm having trouble finding the rules for dividend and capital gain taxation for all these possibilities.