Wall Street is experiencing a surge in passive investing and momentum mania, raising concerns among market observers. The trend has caught the attention of Bill Gross, who has expressed caution about the risks associated with this market behavior. The rapid growth of index-tracking funds and the widespread adoption of risk-on strategies are stirring up fresh angst about the potential dangers posed by this boom across Wall Street. Bill Gross, known for his market insights, is particularly on alert due to the risk-on momentum mania sweeping through the financial sector.