You buy one big block, say 50% of daily volume. Then you move the shares around, in the next few sessions sell smaller blocks through multiple brokers. The key is to buy enough volume to move the price, not so much to make exiting the position difficult. I don't do things like this, but I did see it on lower-liquidity exchanges all the time, and used to trade in small caps where a $10K bid could move the price ~5%... And if I was motivated to sell, the best bet was to break it up into smaller pieces, and sell over the course of a session or two. If daily volume is 50K, and I want to sell 20K, I can't put it all up at once.
Also, on a typical exchange like the NYSE, HKex, Euronext Paris, etc..., the volume is so large you generally don't even bother to look at who's buying or selling. On smaller exchanges you're constantly glued to the screen, looking at the sellers, trying to guess what they're up to.
I imagine company 401ks are managed by in a fairly conservative way. Big positions in fundamentally solid large caps, holding for a long time, selling only when you need to cash out or the price moves beyond a certain range. Traders basically manage their trades in the exact opposite fashion - short, extremely speculative trades, no regard for fundamentals, on smaller exchanges you mess with people's emotions, etc...
Also, on a typical exchange like the NYSE, HKex, Euronext Paris, etc..., the volume is so large you generally don't even bother to look at who's buying or selling. On smaller exchanges you're constantly glued to the screen, looking at the sellers, trying to guess what they're up to.
I imagine company 401ks are managed by in a fairly conservative way. Big positions in fundamentally solid large caps, holding for a long time, selling only when you need to cash out or the price moves beyond a certain range. Traders basically manage their trades in the exact opposite fashion - short, extremely speculative trades, no regard for fundamentals, on smaller exchanges you mess with people's emotions, etc...