Here is the front page of the Financial Times for Tuesday. Nice summary indeed.
There are oil market dynamics in play* in the sub zero price (May contract) but the fundamentals behind the move are:
- Demand has evaporated due to the coronavirus lockdown - MUCH less driving and flying hence lack of demand.
- Oil pumping continued with the product going into storage
- Storage is filling up, hence you'll get paid to take physical
(*If there is any interest I can post more on this).