A recent report by the British Office of National Statistics (ONS) showed that more than 50% the UK's $2.7 trillion stock market was owned by people from outside the United Kingdom. This is because of an increase in international mergers that has led to an increase in shares held by foreign investors. As some critics have said, "Britain is for sale."
The largest share of foreign investment in the UK comes from North America, followed by other European countries. Stock analysts have pointed out that the days when insurance companies and holders of pension funds in the UK held most of the stocks, it is now made up of investors from the United States, parts of the Middle East, China, and Norway. This is due, in part, because of the crash of 2008 that resulted in a major loss for pension fund holders.
Some don't see this as a bad thing. As proponents pointed out, this means that the UK is attracting investment from some of the top firms in the world. Whether that is a positive or a negative for the UK remains to be seen.