U.S. regulators and the company itself warned users of its premium smartphones to immediately turn off and stop charging them.

Aviation authorities around the world have also called on passengers to stop using the devices during flights. About three dozen of the phones, released just three weeks ago, had batteries that caught fire or exploded.

The troubles come at a critical time for Samsung. The company rolled out the Note 7 last month to give it a head start on Apple Inc.’s new iPhone, which were unveiled last week. But that advantage has now disappeared. Samsung shares fell as much as 7.6 percent, on track for their biggest intraday drop since August of 2012. Including a 3.9 percent decline on Friday, Samsung has shed about $19 billion in market value. Battery-making affiliate Samsung SDI Co. fell as much as 6.2 percent to 96,200 won, the lowest on an intraday basis in five months.

(Excerpts from Bloomberg.com)