When I say a lot of news is already known to a select group of people, I'm including official news. Just as there are typically signs when a stock is going to make a big move—indications in the form of daily volume, directional bias, and relative action (i.e., the stock versus the stock of rivals or indexes that cover the industry)—there are also signs when a big media piece could be brewing.
When you are engaged in the market and looking for short-term gains based on reading the tape, there is a powerful temptation to get in ahead of the crowd. Just as one can jump the gun and buy a stock that is on the cusp of a breakout but doesn't break out and instead turns lower in a hurry, so too can one be victimized by tape readings that are compelling. A stock may see a spike in volume but with no news, and many investors jump into the fray only to be disappointed days later. You have to be very careful of these head fakes.
I have been the victim of so many head fakes I've lost count. I have also been deliberately set up a few times. I don't get as many of the calls as I used to, but in the early 1990s my office was like hot-stock-tip central. This is before the Internet became a major communication force.