The Sisters of St. Francis have developed an interesting strategy to try to influence corporations into being more socially responsible. They use their retirement fund to purchase the minimum number of shares needed to introduce resolutions at the annual shareholder meeting and use that leverage to gain private audiences with the CEOs. Other orders have done likewise. However, they do not have enough leverage to really bring about change.
I wonder if it would be possible for a consortium of progressive stockholders to actually gain control of a major corporation. They would need to keep their purpose and connections quiet, to prevent a spike in share price and courting of a "white knight" to prevent a takeover. The big question is, which corporation should be the target? The nuns went for Goldman Sachs. Given that bank's influence on our nation's economic policies (the firm is such a revolving door for future and former Treasury Secretaries that it has long been nicknamed Government Sachs), it's probably a good place to start.