Well, as you can see from the other reply to your original post, there certainly are those who put no credence into the idea of MM manipulation. However, I have been in enough stocks to know that MMs do not simply match buyers and sellers. They do not always play by the rules, as evidenced by NITE's (and others') refusal to follow the new SEC regulations when it comes to showing true bid/ask sizes. I've been in stocks that have nearly 100% short volume on a given day, and since the average retail investor cannot short penny stocks, that leaves the MMs doing it themselves. I've been in stocks that with every buy at the ask, the ask would then DROP. Or, it would be immediately be followed by a 100 share bidwhack where the commission would be 700% higher than the sale itself. You know, things that make NO sense, things that no retail investor would in his right mind do. Proof, I have none. But over the time I've been in penny stocks, I've seen an overwhelming amount of circumstantial evidence that the MMs themselves often want the stock at a certain price, or to go a certain direction. And you can research Level 3, which the MMs have access to, while retail investors only have access to Level 2. That's my take, anyway.