It is my understanding that mms get away with this by making a fair and orderly market for a security. they do not have to cover until they choose to. however, one usually flips before the other. and when just one mm joins our side and starts buying, it's lights out to the rest. i would suggest looking at the sec and finra regs. they both have search options.
Threshold securities are equity securities that have an aggregate fail to deliver position for:
five consecutive settlement days at a registered clearing agency (e.g., National Securities Clearing Corporation (NSCC));
totaling 10,000 shares or more; and
equal to at least 0.5% of the issuer's total shares outstanding.16
Threshold securities only include issuers registered or required to file reports with the Commission ("reporting companies"). Therefore, securities of issuers that are not registered or required to file reports with the Commission, which includes the majority of issuers on the Pink Sheets, cannot be threshold securities. This is because the SROs need to look to the total outstanding shares of the issuer in order to calculate whether or not the securities meet the definition of a "threshold security." For non-reporting companies, reliable information on total outstanding shares is difficult to determine