I cant see any quote for grey markets There is any market maker ? Brokers just combine buy and sell orders from their clients ?
Do you mean "do not exist" rather than "not allowed"? How are quotes "not allowed"? If a market maker starts to publicly quote prices for a grey market security, doesn't the security cease to be a grey market security and become an OTC Pink security instead?
It depends on why it’s gray market. https://www.otcmarkets.com/glossary Grey Market, "OTC" or "Other OTC" is a security that is not currently traded on the OTCQX, OTCQB or Pink markets. Broker-dealers are not willing or able to publicly quote OTC securities because of a lack of investor interest, company information availability or regulatory compliance.