It's something OTC Markets dreamed up to try and legitimize their private trading platform because the SEC has shown an interest in the problems that are getting worse of late.
"The Expert Market is a private market to serve broker-dealer pricing and best execution needs in securities that are restricted from public quoting or trading. Restrictions can be based on issuer requirements, security attributes, investor accreditation and/or suitability risks. Quoting in securities on this market is restricted and OTC Markets does not release quote data directly to investors."
PMDP getting this designation shows that pretty plainly. In fact, a lot of the worst tickers I follow that have been dead for a long time have gotten the designation. It won't mean a thing to them being resurrected so that trading can commence again.
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