Dedugan,
I don't believe that Institutions buying shares at the encouragement of others is illegal, what we're accusing others of is spoofing, not really buying or selling, but making it appear that their are big buy or sell orders to raise or drop the market. An Institution taking a multi-million share position on the open market certainly should help to move the share price up, it's not what most Institutions prefer to do, but if they want a position in a stock, and no major offering is anticipated from that company, they'll purchase from the open market.
Institutions are often the recipient of practically every share issued when a company does an offering. Offerings are often driven by brokers who service Institutions that clearly wish to add major share positions to their portfolio. In general they're priced slightly below current share prices but they bring in substantial funding. Companies not planning such offerings are often tempted to do so when brokerages tell them they have Institutions looking to add millions of shares if they can buy them on the right terms.
Gary
Market Data 
Markets 
AI
