Lenders have shares cleared for sale as a part of the conversion process. Those shares are sold to market makers. The business interaction between note holders, clearing house and market makers allows market makers a way to know the quantity and pricing of shares in advance of the market makers essentially buying from a pool of shares. Market makers are routinely in communication since like any other product the buyer would receive assurances the product will be available at an approximate date at an agreed price, etc. This is not a specific entity providing data for publication. Its how the process of shares being converted then sold to market makers works. This is also why market makers will naked short but it certainly is not the only reason sense market makers can naked short and replace the security with a "like security" prior to getting into what is essentially a default situation.
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