Instead of shares being tradable, they are acquired by serving. Equivalently, one acquires citizenship and the vote, by serving in the military.
However, low-ranking soldiers should not be able to out-vote their superior officers, otherwise the military could not function. You could acquire more shares with rank and length of service, or perhaps a system could function where low-ranking soldiers appointed their officers, for a limited time with the threat of non-renewal, but then had to obey their orders.
Is there any reason why military government must lead to a non-liberal, sclerotic society like Perónist Argentina or Francoist Spain? Or a corrupt society where the military runs large companies, like China? These are certainly error modes. Military personnel do not typically understand liberal economics, so without tradable shares there is no guarantee that sovcorp managers will implement sensible policies. Perhaps 49% of the shares could be tradable.
With a literal military government, where the civil service and ministries are staffed solely by uniformed military, it will be more difficult to attract capable managers who are put off by military life. Or you could get a situation where managers enter the "military" and wear the uniform, but never serve in an actually military capacity.