TOKYO (Reuters) – Shares in Toyota Motor Corp (7203.T) fell for the sixth straight day on Friday as the world’s top automaker’s problems intensified over a recall of millions of vehicles due to faulty accelerator pedals and floor mats.

Toyota shares fell 2.1 percent to 3,485 yen in morning trade in Tokyo. They have lost 15 percent in the last five days.

“Toyota’s stock might fall further until the impact on earnings and profits from the recall becomes clear,” said Hiroaki Kuramochi, chief equity marketing officer at Tokai Tokyo Securities.

U.S. Congressional investigators are seeking e-mails and other documents from Toyota and U.S. safety regulators about the automaker’s recall.

It would be the first congressional review of its kind since the same committee investigated defective Firestone tires linked to deadly Ford Motor Co (F.N) rollovers in 2001.

On Thursday, Toyota said it would extend its safety recall of its most popular cars to Europe and China.

The scale of the fix for the Toyota accelerator pedals has emboldened rivals and could land the Japanese carmaker with hundreds of millions of dollars in extra costs per month.