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 easing to 410 yen, up 7.04 percent.
Shares in ANA climbed 5.07 percent to 207 yen at one point before easing to 206 yen, a gain of 4.56 percent. JAL was up 0.82 percent at 4,255 yen, 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 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.