Many of ETF’s that track US market are priced in GBP in trading212. Does this mean that when buying/selling these equities double currency conversion takes place: USD -> GBP -> USD (provided that my account is in USD)?
What is actually the reason of pricing those ETF’s in GBP while they are domiciled in Ireland?
Vanguard creates versions of its ETFs to trade on the LSE and priced in GBP to appeal to UK investors who do not want to have convert their currency because they are with a broker who has high currency exchange fees. For example, IE00B3XXRP09 trades both as VUSA (priced in GBP) and VUSD (priced in USD). Other ETF providers do similarly.
Ireland is a popular place for ETFs to domicile because of favourable tax treatment. Ireland does not impose any taxes. It has a treaty with the US so withholding tax paid by Vanguard on US dividends is just 15%.
If your account is in USD it is really not a problem to covert to GBP when purchasing. The currency exchange is done with no fee. The bid/offer currency spread is less than 0.01%. So you would have to be trading in and out very frequently for this to have any significant impact on your returns.