"The investor has the benefit of the stock market's daily and changing appraisal of his holdings, 'for whatever that appraisal may be worth', and, second, that the investor is able to increase or decrease his investment at the market's daily figure - 'if he chooses'. Thus the existence of a quoted market gives the investor certain options which he does not have if his security is unquoted. But it does not impose the current quotation on an investor who prefers to take his idea of value from some other source."