Shares in All Nippon Airways and battery maker GS Yuasa surged on Thursday after a report that US and Japanese regulators were preparing to give the green light to the resumption of Dreamliner flights.
Japan's Nikkei business daily said aviation safety bosses in both countries could lift the grounding order on the Boeing 787, which has been parked up around the world since January following incidents involving its batteries.
ANA and its rival Japan Airlines (JAL) have invested heavily in the next-generation plane, and its grounding has played havoc with their schedules, forcing the cancellation of thousands of flights.
GS Yuasa, the company that makes the battery at the centre of the safety probe, saw its Tokyo-listed stocks rocket more than 11 percent at one point, before closing at 404 yen, up 5.48 percent.
Shares in ANA climbed 5.07 percent to 207 yen at one point before easing to close at 204 yen, a gain of 3.55 percent. JAL was up 0.82 percent at 4,255 yen at the close, after climbing 1.90 percent earlier.
All the 50 Boeing 787 planes in service around the world were grounded in mid-January after a series of overheating problems with the cutting-edge aircraft's lithium-ion battery system.
The action came after a battery fire on a parked JAL 787 at Boston's Logan International Airport and an incident in which fumes from a battery forced the emergency landing of an ANA-operated plane in Japan.
The Nikkei said the US Federal Aviation Administration (FAA) has notified Japanese officials of its intention to approve the aircraft for flight in light of the measures manufacturer Boeing is taking.
Japan's Transportation Ministry is expected to lift its own ban once the FAA makes an official announcement, the Nikkei said. The paper did not identify its sources.
In the United States, United Airlines may start flying Dreamliners as soon as late May, it said.
ANA is looking to bring back the Dreamliner for domestic service on June 1 and JAL, which flies the Dreamliner only on international routes, plans to resume in June, it said.
"We can't tell you right now when we will likely lift the ban on the grounding, as we are now in the process of evaluating Boeing's report on their safety measures," an official at Japan's transport ministry told AFP.
"If Boeing shows that it has taken all measures against all possible root causes of the trouble, the aircraft will be able to resume flight again," he added.
Spokesmen at ANA and JAL said they could not confirm the report, adding both airlines were waiting regulators' approval.
FAA Administrator Michael Huerta said Tuesday that Boeing "has completed all required tests and analysis" intended to demonstrate the safety of battery fixes on its 787 jets, suggesting that an end to the grounding of Boeing's cutting-edge passenger jet would come soon.
Huerta in written testimony told the US Senate Commerce Committee that the agency is reviewing Boeing's submission and will give final approval to put the planes back into commercial service when the agency is satisfied that the redesigned battery system meets FAA requirements.
Japan's Chief Cabinet Secretary Yoshihide Suga told a regular news conference he believed regulators were in the final stages of approving the fix.
"The Ministry of Land and Transport and the US Federal Aviation Administration are closely coordinating with each other on the matter," he said.
-- Dow Jones Newswires contributed to this story --