Tesla's Declining Regulatory Credit Revenue Poses Financial Challenge

For years, Tesla has earned billions of dollars from its competitors just for selling electric vehicles.

Regulatory credit sales have been a huge source of revenue for the automaker, which currently faces a sales and profit slump.

Legacy automakers purchase credits from Tesla to keep selling gas-burning cars that would otherwise violate emission regulations and cost them a fine.

But that windfall is about to go away, just when the company may need it the most.