What determines the price of an option is not, therefore, the likelihood in the mind of any one person of its rising or of its falling, but the probability of its moving widely in either direction. The price payable for an option on stocks which fluctuate widely is much higher than upon those which are steady, moving within very narrow limits. For instance, whereas 10_s._ per cent. has been mentioned as an ordinary price for an option on Consols, the price for an option on some American railroad shares would be £4 or £5. As the price of the option depends upon the extent, not the nature, of the fluctuation, it is naturally affected also by the duration of the period over which the option extends. The longer the period, of course, the higher the price. The Stock Exchange Committee does not recognise any bargain, option or otherwise, which extends for more than two accounts beyond the one in which it is begun, which would mean about six weeks at the most; the law of the Stock Exchange evidently aiming at prompt settlement of transactions. The fact, however, that options for longer periods are not officially recognised by no means implies that they are not carried out. Options for three months are quite common, and it may be said that the periods for which options are entered into extend from a day to six months. In the case of day-to-day options, it is taken for granted that the period ends exactly a quarter of an hour before the official closing time of the Stock Exchange, which is half past three o'clock. In the case of options for other periods, it is taken for granted that the period ends with the account in which they fall due, or rather a quarter of an hour before, with the idea of allowing time for making final arrangements. An option may be arranged in January for, say, the end of March account, in which case the period would expire at a quarter to one on the Contango day at the end of that account, the account actually ending at one o'clock. When the time expires, the giver of money for the option has to declare whether he will exercise it or not. If he exercises a call option, he has then to pay the money and receive the shares. If he exercises a put option, he has then to deliver the shares and receive the money. Except in very peculiar circumstances, the option dealer, the taker of the money for the option, will know, when the term arrives, whether it will be exercised or not by merely comparing the existing market price with the option price. A call is not likely to be exercised if the shares can be bought much more cheaply in the market, nor is a put likely to be exercised if the shares can be sold at a much higher price in the market.