The Securities and Exchange Commission (SEC) and the U.S. Attorney’s Office for the Eastern District of New York have filed parallel civil and criminal fraud charges against thirteen people operating a scam in which they cold called their primarily senior citizens victims and pressured them to buy penny stocks which would drive up the price of these low capitalized companies at which point the scammers would dump shares of the same companies they had purchased earlier at lower prices.  This classic pump and dump scam resulted in the scammers taking in more than 14 million dollars in illegal proceeds while their victims lost millions when the stocks reverted to their true value.
TIPS
No one should ever buy a stock in response to a cold call from a telemarketer.  Never make any investment until you have carefully researched not only the investment, but the investment adviser seeking to have you invest your hard earned money with him or her.  The SEC has an interactive website where you can learn about your investment adviser. It is   https://adviserinfo.sec.gov/IAPD/Default.aspx