Nitpick: I think you are getting confused with your reference to 6x. There is federal “guidance” that banks shouldn’t lend to companies beyond that level. That

Nitpick: I think you are getting confused with your reference to 6x. There is federal “guidance” that banks shouldn’t lend to companies beyond that level. That is different from margin lending limits for security trades, which based on a skim of the PDF you linked, seems to be 2x, or in certain cases, up to 7.6x.