Contract law includes lots of rules. The requirement that the terms of the acceptance be the same as those of the offer is the:

Oliver queen buys 100 shares of stock in green arrow archery corporation, a publicly traded company with which he is not affiliated as a director, officer, or employee. he then sells his 100 shares to john diggle. the sec sues oliver because he didn't register the sale of stock to john. who wins? oliver, because the sale falls into the nonissuer exemption oliver, because the sale falls into the private placement exemption the sec, because the transaction is not exempt from registration the sec, because even exempt transactions must be registered with the sec