Just a note about level 2 sw183. A market maker is only obligated to sell (or buy, as the case may be) 100 shares at the price he quotes, no matter how many shares he mentions. For example, market maker NITE might put up a bid price of 30,000 PGLC at .07. If somembody wants to dump 30,000 shares at .07, NITE is obligated to buy only 100. The rest NITE can withdraw.
In other words, level 2 is not what it seems. It is used by market makers to play all kinds of games. Indeed, NITE could post an ask for 30,000 shares and not even have 1000 on hand. His 30,000 ask obligates him to sell only 100--and then only if there is a market order from somebody to buy 100 or more while the posting is up.
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