-- Letting small losses turn into large losses.
-- Refusing to take a loss at all.
-- Overbetting.
-- Bottom fishing/Catching falling knives.
-- Averaging down.
-- Shorting bulls and buying bears.
-- Confusing the company with its stock.
-- Falling in love with a "story."
-- Following the leader.
-- Buying IPOs.
-- Finding the Holy Grail.
-- Overtrading.
-- Excessive tape watching.
-- Being undercapitalized.
-- Letting the tax tail wag the stock dog.
-- Relying on gurus.
-- Thinking this market stuff is easy.
-- Thinking rather than looking.
My personal favorite (for a turn of a phrase), is "catching falling knives".
For a fuller explanation of the items on the list, go to the original piece that the summary came from at Decision Point.
He did almost all of his work in an outlining program called ThinkTank, which he used as a kind of external associative memory to supplement his own. Everything he read, every conversation he had, every thought that occurred, everything got summarized and added to the data base that swelled eventually to 20 million bytes organized in 2000 alphabetical files...Reading, discussion and thinking that Fischer did outside the office was recorded on slips to paper to be entered into the database later. Reading, discussion, and thinking that took place inside the office was recorded directly. While he was on the phone, he was typing. While he was talking to you in person, he was typing. Sometimes he even typed while he was interviewing a prospective job candidate, looking at the screen not the candidate.I've often thought that the most productive academics have what I call "functionial adaptive autism". They seem to have the ability to tune out the outside world for hours at a time when working on a problem. Unfortunately, for some, they find it hard to tune back in. Having read the symptoms of Asperger's, that also seems to fit.