I thought that the funds were subject to standard bankruptcy court proceedings as a company asset, but it turns out you're right. Mea culpa. But it's not simply because they can't keep your money, it's because of the Investment Company Act of 1940 and how the fund is separated from both the parent company and the party that holds the money (usually a bank). Good job by our government back then setting up those regulations to protect investors. Here's a summary: https://www.kiplinger.com/art