I'll respond to your series of posts with one.
1st post.
It's not whether the 40-55 year olds are in the computer industry, it's whether their absence causes the economy to slow down. This slow down induces a poor market, which in turn causes p/e's to contract.
2nd post
The demand for computers has increased several orders of magnitude over the last two decades, without a concomitant increase in the 40-55 cohort.
Two points. First, although not several orders of magnitude there was a quite large increase in the 40-55 year olds that IMO resulted in the economy booming during this period. Secondly, even though there was a radical increase in the numbers of cars and radios from 1929 to 1939, compare the prices of GM and RCA stock in the two periods.
3rd post
I bet the people who sold in 1930 after the crash wish they hadn't, twenty years later.
You might equally well consider those that didn't live until the '50s or weren't "lucky" enough to have pick companies that survived.
That tautology held true in 2000, and 1999, and 1998, and 1997, and 1996, and 1995, and 1994, etc. It wasn't all that useful then, and I don't think it is now.
What do we do if there's a Bear market? I say hold. As I recall, stocks make for the best investment in almost every twenty-year period in history.
From '94 to '00, I wasn't particularly worried about a secular bear. Given the magnitude of the baby boom demographic bulge, I am worried that 2008 to 2027 may be similar to 1929 to 1948. ('Course maybe I should just worry about being around in 2027. <gg>)
lurqer |