Seven investors who say they lost their life savings in a fraud allegedly perpetrated by former GunnAllen Financial broker Frank Bluestein have filed an arbitration claim against the Tampa firm. The investors claim GunnAllen and another of Bluestein's former employers "failed utterly to inquire into, monitor, and prevent" a Ponzi scheme that he allegedly marketed on the side. Several other arbitration claims and lawsuits have previously been filed against GunnAllen, which claims Bluestein deliberately concealed the fraudulent investments from it. GunnAllen denies any wrongdoing.