, with a higher threshold and not retroactive.

The resolution criteria of the 50 markets don't have to be 

 the same, they just need to be similar enough that they can easily be arbitraged against each other.

I will ignore any markets that seem to be trying to manipulate this one, such as one person creating 50 identical markets, or someone placing a large bet on YES in this market right as they create the 50th one on some other event.

If this has already happened prior to market creation, that doesn't count. Must be a future occurrance.