Samsung has lost $22-billion of market value in the past two days as investors take fright at growing alarm over its Note 7 smartphones, the batteries of which have caught fire and exploded. By late yesterday Samsung shares had plunged 11% since Friday, with both US regulators and the company itself advising people to switch off their Note 7s and refrain from charging them until new batteries could be installed.Earlier, aviation authorities and airlines called on passengers to stop using the gadgets on flights.The stock drop suggests the damage to Samsung's brand could go well beyond the early estimates of $1-billion for a single product's recall. The company has spent heavily on marketing its name in past years and had hoped to get a head start on Apple by unveiling its device weeks before the new iPhone emerged. That advantage has disappeared."Samsung's nightmare is just getting worse," said Bryan Ma, vice-president at market researcher IDC. It is possible that airlines, rather than isolating Note 7s, may ban all Samsung phones given the difficulty of differentiating between models."If true, then the Note 7 could end up dragging down the rest of the portfolio," said Ma.Samsung announced the recall last week after about three dozen smartphones were found to have batteries that spontaneously ignited and melted the phone casings. Since then many more incidents have been reported.On Saturday Samsung told users in South Korea to stop using the devices and to bring them to its service centres - less than a month after they debuted.Note 7s with new batteries are due to become available on Monday. Samsung said about 2.5million phones had been shipped around the world before their recall.The US Consumer Product Safety Commission and Samsung are in talks on an official recall of the devices as soon as possible. Almost all CPSC recalls are done voluntarily in conjunction with a company and the scope of any action on the Note 7 may be identical to what Samsung has already suggested to consumers."The uncertainty over the Note 7 recall has grown following the tough reactions from the US," said Lee Seung Woo, an analyst at IBK Securities in Seoul. "Samsung has to settle this situation as early as possible by replacing every Note 7 device to reassure customers. In the worst case scenario, Samsung may have to consider discontinuing Note 7 sales for a time."The CPSC advisory came on the heels of warnings from aviation regulators in several countries and airlines. The European Aviation Safety Agency on Friday cautioned flyers against packing them in checked bags.Similar moves have taken place in India. And Singapore Airlines and US carriers have also taken action."The market certainly thinks this is going to cost more than $1-billion," said Anthea Lai, an analyst with Bloomberg Intelligence. ..