Well, the specialist is responsible for making a market for the stock he/she is handling. Now that can cover a lot of ground. The big boys are also out there trying to get/sell shares at the best price. There are a number of situations that could work, but say there is a buyer that wants a lot of shares lower than the current price and the market is currently rather slow. Also assume there are a significant amount of shares at various prices out there waiting to be sold through stop losses. Without a lot of buyers the specialist can offer his shares driving the price lower and take out the stop losses rather quickly at which time he then starts buying for the large account and recovers his own shares. The sudden drop also seems to bring out more sellers (day traders?).
The effect is that the stops get taken out, the buyer gets some or all of his shares, the specialist recovers his shares at a lower price and the price returns to where it was before.
I don't know how legal/ethical such actions are, but they seem to fall under the purview of the specialist’s job to create a market. Having watched the market for many years I've seen what appears to be the above scenario happen many, many times. If you’re following the market Monday you may see it happen again.
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