The prize is for the main draw in the Oct. 22, 2011, Lotto 6/49. The winning ticket was sold in Quebec, but so far no successful winning claim has come forward.
Loto-Québec said Monday that its recent publicity push about the unclaimed prize generated 450 responses and it looked into 130 of them. Fifty cases are still under examination, the lottery corporation said, but the chance of finding the winner among those is "is less and less likely."
If the prize isn't awarded, it would be the biggest unclaimed win in Loto-Québec's history.
The money would go back into the national Lotto 6/49 prize pool and be used for bonus and special draws.