First of all, MM's can't buy and sell shares for themselves. That would make them traders, which is illegal.
Second, they have no concern about which direction the share price goes - they make their commission on every trade, but nothing more.
Mm's display their spread. That means if you offer shares within their buy, they will buy them. If you buy shares within their spread, they will sell them. They can change their spread, but they cannot buy or sell outside of their spread.
Anyone that buys or sells at 'market' gives MM's free reign to open their spread, to immediately consume the trade. That's why, when you buy or sall at market, each tranch will usually be at a different price. It is the spread changing that causes that.
BUT, mm's can't just 'buy' shares and wat for their value to increase, then sell them. NONE of the tactics attributed by traders here are actually MM activity. It is TRADER activity, with MM's implementing the buys and sells.
They CANNOT TYRADE. They are brokers - much like cashiers in stores. That is ALL THEY CAN LEGALLY DO. And, every trade is recorded forever, and fully auditable. If an MM was caught trading like a trader, rather than acting as an MM, it would immediately be obvious, and the SEC could take immediate action. That is an illegal practice, and it DOES NOT HAPPEN. The market is fully automated, and follows the law. The amount of money that could be made on penny stocks is virtually nothing, compared to the daily income of any MM - they compete against each other to complete buys/sells, they do NOT compete against US.
