One other consideration is whether the investing activity is taxed as capital or income. Putting your portfolio in a company ring-fences any trader/income status to that portfolio so any other capital gains in your own name say regarding your own business or some long term interest like property or shares in a family company are taxed as capital and not tainted by active trading in the company. The downside is that losses in the company cannot be offset against gains in your own name and vice versa. I moved my portfolio into a company but as Simon says there are both advantages and disadvantages of having done so
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