As I mentioned before, I did trade pennies at one time using margin but I did have a good amount of money in blue chips in the same account. This was over five years ago and I don't know what they allow nowadays because I don't trade using margin anymore. I guess it is up to the broker but you can read about it here:
Not all stocks qualify to be bought on margin. The Federal Reserve Board regulates which stocks are marginable. As a rule of thumb, brokers will not allow customers to purchase penny stocks, over-the-counter Bulletin Board (OTCBB) securities or initial public offerings (IPOs) on margin because of the day-to-day risks involved with these types of stocks. Individual brokerages can also decide not to margin certain stocks, so check with them to see what restrictions exist on your margin account.
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