Shares of Liquidity Services (LQDT) were down about 7% in early afternoon trading Thursday, marking the second straight day of significant declines for the online wholesale and surplus seller. Shares were down 7.2%, near 48.50, a two-month low. They fell 8.8% Wednesday, on concerns over the company's profit margins. A comment about the company's slowing margin growth at an investment conference Tuesday by Jim Rallo, Liquidity's chief financial