That is a loaded question. Penny stock trading is very volatile and dangerous so be careful. While they are attractive because you can purchase up a lot of shares at low cost, you basically are "getting what you pay for." Most penny moves are temporary and 9 out of 10 will retreat back, so don't be holding them - take a profit immediate. Know how to check their outstanding, if their filings show dilution with convertibles, how to see if there is a promo going on, and don't believe any pumpers. Don't ever fall in love with a penny stock - even if they have a cure for cancer. I have supplied you here with a few links to past answers regarding pennies. Read them all:
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