<p>I haven’t looked at the list of students in a selective financial math program, but I wouldn’t be surprised if it had a large percentage of foreign students for the following reasons:</p>
<ol>
<li><p>Math majors from prestigious American universities can go straight into a quantitive finance career with no need for a Master’s degree.</p></li>
<li><p>American students as a group seem rather averse to the idea of spending $80K on a Master’s degree when they could be getting the same education for free in a PhD program (with the option to drop out after the Master’s if the thesis becomes too cumbersome).</p></li>
<li><p>Pure math has more prestige in the US than in many other countries. In the US, it seems that many of the brightest math students want to have an academic career. In many other countries, the brightest want to do applied stuff and earn lots of money.</p></li>
</ol>