Shareholders still own their shares, but the shares no longer have a ticker/symbol and the shares cannot trade on any public market.
Sigma Gold Corp. would need to submit full disclosures of operations, finances, share structure(s), etc. to OTC Markets to be compliant to Rule 15c2-11, and then the company would need to ask a Market Maker to submit a FORM 211 to FINRA to reinstate the stock ticker for quotations. Since the stock symbol was deleted by FINRA for being an inactive security (ie., no trades in a prolonged timeframe) it is quite rare for a company to go through the elaborate processes to have the ticker reinstated.
To bite the worm of incite is to bite the HOOK of the antagonist . They win .
