A lot of people have had problems with them IIRC. There are several that simply refuse to allow investors to trade a bunch of penny stocks that are on a special trade for trade list (I forget the technical terms), that restricts naked shorting completely by MMs, requiring the broker to have the shares in hand in order to sell them, and there was a change in the cost structure for the brokers to trade those kind of shares, they black listed them to avoid the higher overhead costs. It was big deal about 9 months ago, and turns up periodically on some of the penny stocks, especially the more shady ones.
Only found two stocks, China fraud stocks I could never buy at Fidelity (or elsewhere in the USA), and they were deep in SEC investigations at the time.
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