The Expert Market is simply a subset of the OTC Grey Market. Since shares are not quoted by MM's, the Expert Market is an effort by OTC Markets to facilitate shareholder trades among different broker/dealers.
Here's an example. Johnny uses Schwab and Susie uses Fidelity. Johnny wants to sell 1,000,000 KGET at .0001. Johnny calls his representative at Schwab, asking the rep to handle the transaction. The Schwab rep checks "in-house" and there are no buyers interested in buying at SPRV .0001. So now what? The Schwab rep needs to go to another broker/dealer to find a buyer. Susie, a Fidelity customer, wants to buy 1,000,000 KGET at .0001. The Expert Market is simply an electronic means of matching these buyers and sellers for stocks that are trading on the Grey Market. Simplistically, the Expert Market is an electronic version of the Grey Market. All trades are still "matched trades". It is not an auction, as is normal trading.
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