Please answer the following question from a financial perspective. Please provide some website references to back up your answers. Thank you!

We've seen a significant increase in shareholder activism in recent years, particularly from large institutional shareholders. One of these areas is that shareholders may now voice opinions on senior management compensation (though not a binding voice). However such activism extends much further to include proposed mergers, acquisitions or spinoffs. Provide some recent examples where shareholder activism has affected a company's performance or actions, and discuss the consequences of this.