Wall Street’s self-regulatory body has been probing Bank of America Merrill Lynch over its failure to detect the activities of a former financial adviser, who pleaded guilty to helping a client cover up an insider-trading scheme and launder the proceeds, said a source familiar with the matter. The Financial Industry Regulatory Authority (FINRA), which has been in discussions with Merrill (BAC.N), may take enforcement action against the bank, most likely citing its alleged shortcomings in complying with anti-money laundering regulations, the source said.