The Theory of Stock Exchange SpeculationCrump, Arthur
General
The Theory of Stock Exchange Speculation
Crump, Arthur
Speculation
facilities afforded by “time-bargains” to operators who have a little
money, just sufficient to enable them to keep afloat as speculators in
fair weather. The first serious disturbance that violently agitates
prices sweeps them away in a shoal.
The question which a sensible speculator will ask himself before he
begins to operate is, What are the risks incurred of losing his all at
one stroke? De Morgan, in his book on probabilities, says in Chapter V.,
on the risks of loss or gain, “A man should not hazard his all on any
terms; but in ventures the loss of one of which would not be felt, we
may suppose the venturer able to make a large number of the same kind;
in which case the common notions of mankind reinforced by the results of
theory, tell us that the sum risked must be only such a proportion of
the possible gain as the mathematical probability of gaining it is of
unity. For instance: suppose I am to receive a shilling if a die, yet
to be thrown, give an ace; in the long run, an ace will occur one time
out of six, or I shall lose five times for every time which I gain. I
must, therefore, make one gain compensate the outlay of six ventures, or
one-sixth of a shilling is what I may give for the prospect, one time
with another. But one-sixth is the probability of throwing the ace.
_Principle_—Multiply the sum to be gained by the fraction which expresses
the chance of gaining it, and the result is the greatest sum which
should be given for the chance.”[3] “A man should not hazard his all
on any terms.” Does a man who enters upon a career of speculation take
the trouble to consider at starting whether or not his first operation
places him in a position in which he hazards his all? There is not
probably one speculator in a hundred who ever thinks of it at all. We
will suppose a man to be worth £200 in cash as his all, applicable to the
payment; of losses. It may safely be stated that numbers of speculators
open accounts with a less sum, in fact a considerable proportion of
speculative operations are entered upon in reality without any funds
at all; misfortunes in other vocations being frequently followed by
gambling in the Stock markets. A speculator with £200 to pay losses with
is in this position if he buys, for instance, for the rise £5,000 of any
English railway stock; a fall of 5 per cent., which even in two or three
days is nothing very extraordinary, carries him £50 “under water.” What
can he reckon upon on the other side, by keeping the account open, that
is a mathematical certainty like the occurrence of an ace one time out
of six in the long run in throwing the die? If he be exposed to such a
loss at any moment as that mentioned, the risk is an absurd one to run
if there is not at least an equal chance of a similar rise, and several
times £250 in reserve. But all experienced in Stock Exchange fluctuations
know that upward movements are, as a rule, gradual, a rise of 1 per
cent.
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