If, by published you mean published in a peer-reviewed journal, then no. Studies are registered before they start, but clinical trials fail or are withdrawn for various reasons (like safety problems, lack of funding, etc).
I imagine that registered studies that are completed are published if they have positive results, or negative results that contradict other well-known positive results. There's no reason not to publish if you get a good or interesting result. But publication can take years, so I don't think it's particularly unusual to see a completed study without a corresponding publication.
But again, the specific cases you linked predate the current registration and reporting requirements.
Sorry, but publication of negative results only happens in a number of cases.
1) Research is carried out by academics with no ties to phamaceutical companies.
2) The negative results make a competitors drug look even worse.
If neither of these things are true, then negative results just sit in a file-drawer somewhere. Compulsory registration (clinicaltrials.gov) will help with this for new medicines, but this will take years before we have any decent information
