The World Series of Poker has announced the Spring Online Championships, the largest ever online tournament series to be held in the regulated US markets.

$4 million is guaranteed across 100 events over the course of a month. It is the biggest series guarantee from any online poker operator working the US regulated states of Nevada, New Jersey, Delaware and Pennsylvania.

A mixture of knockout, re-entry, turbo and freezeout tournaments make up the schedule. Buy-ins start from $10 and go up to $1000. A $300,000-guaranteed Main Event will play out at the end of the series on May 3.