a good tooth, gets no gold
Whisper stock is shares in a company that is rumored to be the target of a takeover offer. The reason for the whisper is that any such talk must be kept quiet for one of two reasons. One, if the rumor has some validity, those who believe it will want to act on it before the rumor spreads. Two, if the whispering actually turns out to be true due to a leak of a confidential mergers and acquisition (M&A) transaction, no one wants to be brought in for questioning by the enforcement unit of a regulator or an investigator from the Department of Justice. There may be a surge in trading volume and upward price pressure on shares of a whisper stock. Once that happens and gains wider notice by the market, the stock will no longer be a whisper stock.