Share your insights or perspective on the financial matter presented in the input.

Why do US retirement funds typically have way more US assets than international assets?
There are a few main economic reasons given why investors show a strong home bias: Interestingly, though if you ask investors about the future of their home country compared with other countries they will generally (though not always) significantly overestimate the future of their own country.  It is difficult to definitively say what drives investors but this psychological home bias could be one of the larger factors. Edit in response to the bounty: Maybe this Vanguard article on their recommended international exposure is what you are looking for though they only briefly speculate about why people so consistently show a home bias in investing.  The Wikipedia article mentioned above has some very good references and while there may be no complete answer with the certainty that you seek (as there are as many reasons as there are investors) a combination of the above list seems to capture much of what is going on across different countries.