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why did my number of shares of stock decrease?
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during a stock split the only thing that changes is the number of shares outstanding.  typically a stock splits to lower its price per share.  sometimes if a company's value is falling it will do a reverse split where x shares will be exchanged for y shares.  this is typically done to avoid being de-listed from an exchange if the price per share falls below a certain threshold, usually $1.  again the only thing changing is the number of shares outstanding.  a 20 for 1 reverse split means for every 20 shares outstanding the shareholder will be granted one new share. example x co. has 1,000,000 shares outstanding for a price of $100 per share.  it does a 1 for 10 split.  now there are 10,000,000 shares outstanding for a price of $10 per share. example y co has 1,000,000 shares outstanding for a price of $1 per share.  it does a 10 for 1 reverse split.  now there are 100,000 shares outstanding for a price of $10. quickly looking at the news for asti it looks like it underwent a 20 for 1 reverse split.  you should probably look at your statements and ask your broker how the arithmetic worked in your case. investopedia links for reverse stock split and stock split
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