I uses yahoo or google historic daily EOD data. I see occasionally sometimes there are daily quotes that reports zero open and zero vol, or zero vol but different price for open/high/low/close. I do not understand it. Is it just an error or something that makes sense. Anyone knows?
You get what you pay for. Maybe zero volume just means it didn't trade that day (e.g. due to trading halt/suspension). Alternatively it could just be bad data - this is likely if there is a range for the day (high different to low). Zero open is clearly garbage.
Thanks anyway. But yours are just obvious. Maybe there are other meanings of zero prices traded. Just do not understand why. Someone with deep insight may know.
I have deep insight. Assuming the data is correct, zero volume means there were no trades that occurred that were eligible to increment the volume for that security for the day. Zero open is garbage - if trades occurred on a day that were eligible trades to affect the "last sale" then there is an open. See the CTA rules if you want the technical details. Best advice: Avoid low liquidity stocks.
Thanks again. I found some explanation on price zero stock at http://finance.zacks.com/happens-stocks-fall-zero-8531.html But it still does not explain what difference is between zero stock and worthlessness.
That's a bad article. Stocks don't fall to "zero" upon delisting. They are tradeable on the OTC market, sometimes at fractions of pennies, but there is still a market for submitting bids and offers. You were asking about "zero open" - which means the open price is zero - which is nonsensical. It either traded or it didn't, and it certainly did not trade at a price of zero.