Newsgroup: it.economia.borsa
Titolo: Cadute e risalite improvvise?

Perdonate la mia totale ignoranza, ma che significato ha quando un titolo, 
in pochissimi minuti, scende improvvisamente di un 2/3 % o anche più e poi, 
sempre in pochissimo tempo ritorna al valore precedente, o viceversa?
Grazie a tutti, ciao,
Giorgio 
 

 sempre in pochissimo tempo ritorna al valore precedente, o viceversa?
 
Significa che e' molto volatile. Di solito succede in situazioni di poca 
liquidita', come minimo poca su quel titolo o anche poca in generale.
 
 
 
 
-- 
Memento: 9.11.2011 MEDIASET -12%

 
 
"doppio.massimo"  ha scritto nel messaggio 
news:fV2Jq.113512$GZ3....@tornado.fastwebnet.it...

Grazie, ciao e buon Natale,
Giorgio 
 

 ha scritto nel messaggio 
news:jd2b68$j9b$1...@speranza.aioe.org...

For the past nine years, I have taught an investing
course to a group of graduate business students at an Ivy
League university. Needless to say, this is a pretty smart
group of students. Each year, on the first day of class, I
walk in and open the newspaper to the financial section.
Found there are pages and pages of tables with lots of
numbers in tiny print. (Sounds great so far, right?) Anyway,
posted in these tables is a list of company names, and
next to each name is a bunch of prices.
"Call out the name of a big, well-known company," I
say. The students come up with companies like General
Electric, IBM, General Motors, and Abercrombie &
Fitch. Actually, it doesn't really matter what companies
the students shout out. My main point is so easy to
make, any company name in almost any industry, large or
small, well-known or not, will do. The result is always
the same.
I look in the paper next to General Electric and read
off the numbers. "It says here that the price for one share
of General Electric was $35 yesterday. It also says here
that the highest price that General Electric shares have
sold for over the last year was $53 per share. The lowest
price for a share over the last year was $29.
"For IBM, it's the same thing. You could have purchased
one share of IBM yesterday for $85. Over the past
year, shares of IBM have sold for as much as $93 and for
as little as $55.
"General Motors sold for $37 per share yesterday.
But over the last year, shares have sold for between $30
THE LITTLE BOOK THAT BEATS THE MARKET [27]
and $68. For Abercrombie & Fitch, which was selling for
$27 per share yesterday, the range of prices per share over
the last year has been between $15 per share at the lowest
and just over $33 per share for a high price."
I then point out that that's a pretty wide range of prices
for shares and a pretty short period of time for them to
change so much. Looking at the price for shares over a twoto
three-year period would give us an even wider range.
So here's the question that I always ask: How can this
be? These are big, well-known companies. Each of these
companies has divided its ownership into millions (and
sometimes billions) of equal shares, just like Jason did
with his gum shops. Initially, companies sell their shares
to the public (to both individuals and big institutional
investors). After that, though, the people who buy these
shares are free to sell them to anyone they want.
Each day the newspaper lists the names of thousands
of companies and the price at which people have been
buying and selling an ownership share in each. The trading
back and forth of these ownership shares takes place
in a number of locations and over computer networks.
These ownership shares are referred to as shares of stock,
and collectively, this buying and selling activity is referred
to as the stock market.
A company as large as IBM or General Motors might
have divided its ownership stake into something like a
[28] JOE L G RE E N B LATT
billion equal shares. That means that if at one point during
the year you can purchase one share of General
Motors for $30 (and for our example we assume the ownership
of General Motors has been divided into 1 billion
equal pieces, or shares), then the implied price to purchase
the entire company (all 1 billion shares) would be
$30 billion. However, if at some point during the same
year, General Motors shares could have been purchased
for $60 each, that would indicate that the cost to purchase
all of General Motors would be $60 billion.
So I ask the question again: How can this be? Can the
value of General Motors, the largest car manufacturer in
North America, change that much within the same year?
Can a company that large be worth $30 billion one day
and then a few months later be worth $60 billion? Are
they selling twice as many cars, making twice as much
money, or doing something drastically different in their
business to justify such a large change in value? Of
course, it's possible. But what about the big price changes
in IBM, Abercrombie & Fitch, and General Electric?
Does something happen each and every year to account
for large changes in the value of most companies?
Remember, every year the results are the same. For
pretty much any company that my students name, the
range of high and low prices, over the course of only one
year, is huge. Does this make sense? Well, to save the
THE LITTLE BOOK THAT BEATS THE MARKET [29]
class time (and since my attention span is usually a matter
of seconds), I usually blurt out the answer. No! It makes
no sense that the values of most companies swing wildly
from high to low, or low to high, during the course of
each and every year. On the other hand, it seems pretty
clear that the prices of the shares in most companies swing
around wildly each and every year. All you have to do is
look in the newspaper to see that that's true.
So I ask my room full of smart, sophisticated students
to try to explain why. Why do the prices of all these
businesses move around so much each year if the values
of their businesses can't possibly change that much?
Well, it's a good question, so I generally let my students
spend some time offering up complicated explanations
and theories.
In fact, it's such a good question that professors
have developed whole fields of economic, mathematical,
and social study to try to explain it. Even more incredible,
most of this academic work has involved coming up
with theories as to why something that clearly makes no
sense, actually makes sense. You have to be really smart
to do that.
So why do share prices move around so much every
year when it seems clear that the values of the underlying
businesses do not? Well, here's how I explain it to my
students: Who knows and who cares?
[30] JOE L G RE E N B LATT
Maybe people go nuts a lot. Maybe it's hard to predict
future earnings. Maybe it's hard to decide what a fair
rate of return on your purchase price is. Maybe people
get a little depressed sometimes and don't want to pay a
lot for stuff. Maybe people get excited sometimes and are
willing to pay a lot. So maybe people simply justify high
prices by making high estimates for future earnings when
they are happy and justify low prices by making low estimates
when they are sad.
But like I said, maybe people just go nuts a lot (still
my favorite). The truth is that I don't really have to know
why people are willing to buy and sell shares of most companies
at wildly different prices over very short periods of
time. I just have to know that they do! Why is this helpful?
Let's think about that.
 
 
 
Joel Greenblatt - The Little Book That Beats The Market - 2006 
 

 For the past nine years
 
sorry mr. Doji we are Italian people ! ! Thanks