Is there a government-mandated resource that lists the shareholders of a public company?
No, there is no such list, as the other answers mention it is practically impossible to compile one.  However you can see the institutional investors of a public company.  MSN Money has this information available in a fair amount of details.  For example see the Institutional Investors of GOOG
Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Is there a government-mandated resource that lists the shareholders of a public company?

### Response:
No, there is no such list, as the other answers mention it is practically impossible to compile one.  However you can see the institutional investors of a public company.  MSN Money has this information available in a fair amount of details.  For example see the Institutional Investors of GOOG