Dash8400: Wouldn't that imply that the company was willingly witholding material news for the exercise of these warrants?

Well, in many cases you have creative leeway.

Sure, if a lab explodes, there's no choice as to announce that immediately. But if you want to "withold" e.g. the announcement of a new CEO, let him sign on the dashed line only when the appropriate time for a news release has come. Before he signed, you don't have a new CEO and therefore nothing to announce. Or if you want to "delay" the announcement of a technical goal, you could run just another test to make sure. And another one. And another one. You get the idea.

And if you are under NDA, you would need permission of your business partner.

And the news release will always have to be rubber-stamped by several stakeholders of your own company, which will take time – sometimes more, sometimes less.

Disclaimer: I am not suggesting that POET Technologies is doing that. I am just generally pointing out possibilities.