The hedge fund shareholder activist is against Lipton's plan to revise the Securities & Exchange Commission's rules which would force investors to stop building stakes in companies once they own a five per cent stake. It would also make them give public details of their plan. Mr Ackman has attacked lawyers in his quarterly newsletter, saying that they are the only people who consistently oppose his style of activist investment. He claims the principal proponents of shutting down shareholder activism are not investors, but legal advisors who 'defend' companies from activists and profit from this activity. Martin Lipton is the 'go to' lawyer when companies are targeted by shareholder activists.