The Wolf's scam was as follows (this is from memory, so there may be holes in it, but I think I got the gist of it)
His firm would underwrite new stocks for IPO at $5 per share
I believe the firm who underwrites it, legally can only own 5%of the stock.
He would have other firms, people, etc that he would guarantee shares of the IPO, IF they promised to sell it back to him at $6. The buyer gets to make 20% ($1) risk free for doing nothing.
The street sees that the firm is buying back all the stock at $6, so the street assumes they value the stock more, so the price gets artificially inflated and so on......
His traders make a shit ton of commission, and the firm makes a shit ton in sales.
For galeniko's question, the spread between the bid / ask was huge on the pennies - i.e. stock was .39 cents, but cost 60 cents to buy, so the broker got to keep a lot more. (I think it's something like this - I'm not in the market).