What are some of the reasons people buy S&P500 listed on the US market and subject themselves to 30% withholding tax? I understand that Ireland domiciled ones only have 15% tax.?

Hey... they do have an Ireland-domiciled ETF that tracks the S&P500 Index - ie CSPX. However, please do note that the barrier of entry for that ETF is appx $3k USD.​​​

Hi Anon,

If you're looking to trade frequently (move in and out of the market freqently), the US markets would be a better choice for the reasons Ethan mentioned, i.e. better liquidty, tighter spreads and lower commissions

However, if you're in for the long run, the benefit of lower witholding tax will definietely outweigh the cost of the higher expense ratio of Ireland-domiciled ETFs.

To purchase Ireland-domiciled ETFs, you would need access to the LSE or other European exchanges. Currently, the cheaper brokers I am aware of that have access to these exchanges are Saxo and IBKR.​​​