Reza Dibadj has posted this draft on SSRN (University of San Francisco Law Review).  Here is the abstract:

On January 21, 2010, in a 5-4 opinion, Citizens United struck down § 203 of the Bipartisan Campaign Reform Act of 2002 which prohibited corporations and unions from using general treasury funds for “electioneering communications.” The vibrant commentary emerging from the opinion focuses, as one might expect, on whether the majority was correct in bestowing broad First Amendment rights on corporations and unions.

This Essay, however, emphasizes an undertheorized and often overlooked issue that Citizens United, perhaps unwittingly, brings to the fore: the First Amendment rights of shareholders. The core of my argument is simple: the opinion all but ignores these rights, and in doing so, is a signpost in the march away from shareholder capitalism.

The argument is developed in two principal sections. Part I explores the fundamental problem in Citizens United – the oversized First Amendment rights bestowed upon organizations such as corporations and unions – and the thoughtful emerging critiques that have emerged in response to the majority’s bold language. Part II argues that shareholders, like union members, have First Amendment rights that are trampled upon if the corporation is given free rein to engage in political speech. It concludes by responding to three powerful critiques of the notion that shareholders should have free speech rights: corporate law already protects them, they can simply divest their holdings if they do not agree with the corporation’s speech, and corporations are not state actors against whom constitutional rights may be asserted.